Aganglionosis can be diagnosed by evaluation of either submucosal or myenteric ganglia. Since in either instance the pathologist must establish absence of ganglion cells, adequate sampling is essential and the recognition of ancillary histopathological findings that correlate with aganglionosis can be helpful. In most centers, initial diagnosis of HSCR is based on histopathological study of suction rectal biopsies (Qualman et al. 1999). Diagnostic biopsies must be taken at least 1–1.5 cm proximal to the anorectal squamocolumnar junction, measure >2 mm in diameter, and include sufficient submucosa (Aldridge and Campbell 1968; Weinberg 1970; Venugopal et al. 1981). Typically, about one-third of the cross-sectional area of a biopsy should be submucosal tissue (Fig. 7.2). Although a suboptimal biopsy may exclude the diagnosis if submucosal ganglion cells are present, biopsies that include squamous epithelium or too little submucosal tissue are inadequate to establish the diagnosis of HSCR (Fig. 7.2). Squamous epithelium indicates a biopsy too close to the anorectal junction, where physiological hypoganglionosis exists normally.

In principle, a single, adequate-size suction biopsy from the appropriate location is sufficient to exclude or diagnose Hirschsprung disease. Unfortunately, contemporary biopsy devices do not allow direct visualization of the anorectal canal and the location of a biopsy relative to the squamocolumnar junction is a rough estimate. However, the barrel of the biopsy device is scored so that the relative positions of multiple biopsies can be assessed. In order to reduce the likelihood of an inadequate sample and to facilitate the diagnosis of very short-segment disease, many centers advocate routine procurement of multiple biopsies at varying estimated distances from the anorectal junction (e.g., 1, 2, and 3 cm) (Qualman et al. 1999; Kapur 2009). In patients over a year of age, especially older children or adults, suction biopsy may be inadequate because the submucosa is thicker and more fibrous and submucosal ganglia are more widely spaced than in infants. Some surgeons opt for a deeper biopsy (e.g., incisional or forceps biopsy) in place of suction biopsy in toddlers and older patients.

When properly oriented and sectioned adequately (75–100 levels), H&E-stained, paraffin-embedded sections are generally sufficient to exclude the presence of submucosal ganglion cells and suggest the diagnosis of HSCR. Recognition of ganglion cells is generally easy, particularly with older patients, because the neuronal cell bodies have “mature” cytological features including abundant cytoplasm with basophilic Nissl substance. In neonates, especially premature infants, identification of ganglion cells is more difficult, because their “immature” cytology can be confused with endothelial cells, glia, or lymphocytes (Fig. 7.3). Nonetheless, experienced pathologists usually can discriminate even immature ganglion cells in H&E sections without any special techniques.

The presence of hypertrophic nerve fibers is observed in many but not all cases of HSCR and helps establish the diagnosis (Monforte-Munoz et al. 1998). The hypertrophic nerves that exist in most patients with HSCR arise from extrinsic autonomic and sensory fibers, which enter along with vessels from the perirectal region and project for a finite distance rostrally (Meier-Ruge et al. 1972a; Mebis et al. 1990). It is the density and thicknesses of these fibers that increase in HSCR, giving rise to the “hypertrophic” nerves that are frequently, but not always, observed in the myenteric plexus, submucosa, and mucosa of HSCR patients (Fig. 7.4) (Howard and Garrett 1970; Tam and Boyd 1990; Wedel et al. 1999). In the rectal submucosa of a neonate or young infant, a nerve is considered hypertrophic when its thickness exceeds 40 μm (Monforte-Munoz et al. 1998). However, nerves as thick as 50 μm are present in toddlers and older children. Therefore, the patient’s age and density of hypertrophic nerves need to be considered, and the presence of a single thick submucosal nerve should not be regarded as diagnostic of aganglionosis. Because extrinsic nerves only project for a finite distance proximal to the rectum (Fig. 7.5), hypertrophic innervation may not be observed in biopsies taken rostrally in patients with long-segment disease (Fig. 7.6) (Meier-Ruge et al. 1972a). Furthermore, extrinsic nerve hypertrophy of the rectum may not be observed in patients with combined deficiency of intrinsic ganglion cells and other peripheral ganglia (probably more common with long-segment HSCR) or very premature infants with delayed extrinsic innervation.

The average submucosal biopsy is approximately 3 mm across and the average distance between submucosal ganglia varies with age, but is probably about 500 μm and contains 2–7 ganglion cells, each of which measures 20–30 μm in diameter. With 3–5 μm-thick paraffin sections, ganglia are missed in many random sections. Therefore, it is important to evaluate numerous sections (>75). With an adequate, well-oriented, not crushed, H&E-stained biopsy, one can be fairly confident about the diagnosis of HSCR simply by careful examination of each section. Absence of ganglion cells and the presence of multiple unequivocally hypertrophic nerves are diagnostic. In this situation, the presence of certain ancillary features of HSCR can be quite helpful, but is not required. The problem is that very often the biopsies are suboptimal due to paucity of submucosa, “crush” artifact, or both. For these cases, AChE histochemistry and calretinin immunohistochemistry are particularly valuable.

The frequent, but variable, presence of abnormally thick and numerous AChE-stained nerve fibers in the muscularis mucosa +/− lamina propria can be used to confirm the diagnosis, particularly when neither ganglion cells nor hypertrophic nerves are observed (Meier-Ruge et al. 1972b; Chow et al. 1977). The histochemical reaction used to visualize extrinsic nerve fibers only works with frozen sections of fresh or appropriately fixed tissues. Paraffin embedding inactivates the enzyme. Therefore, centers that perform AChE histochemistry regularly require at least two biopsies, one of which is frozen for AChE histochemistry and the other embedded in paraffin for H&E-stained sections.

The pattern of AChE staining in the rectum of normal children varies with age and includes staining of nerves in the submucosa and small fibers in the muscularis mucosa (Fig. 7.7). Usually, the latter are confined to the inner half of the muscularis mucosa. Some, but not all, of the rectal submucosal biopsies from HSCR patients contain more densely packed, large, AChE-positive fibers through the full thickness of the muscularis mucosa (Schofield et al. 1990). However, other abnormal patterns are also encountered, which sometimes are subtle and difficult to recognize (Pacheco and Bove 2008). In addition, prominent AChE-positive fibers may be present in the lamina propria. Lamina propria involvement should not be relied upon too heavily because hypertrophic nerves are restricted to the muscularis mucosa in biopsies from a significant subset of HSCR patients (Schofield et al. 1990).

Calretinin immunohistochemistry is an alternative ancillary diagnostic technique that is employed much like AChE histochemistry in the analysis of suction rectal biopsies. Calretinin is a calcium-binding protein that is expressed by a subset of submucosal and myenteric ganglion cells, some of which extend neurites into the mucosa (Furness 2006). In aganglionic suction rectal biopsies from an HSCR patient, calretinin-immunoreactive neurites in the lamina propria and muscularis mucosae are absent (Fig. 7.8) (Barshack et al. 2004). Be aware of the fact that calretinin-positive neurites may persist in the extrinsic nerves of the submucosa or myenteric plexus. The important diagnostic feature of aganglionosis is absent immunoreactive small nerves or individual neurites in the lamina propria and muscularis mucosae. In the context of appropriate positive and negative control sections, absent calretinin immunoreactivity has been shown to be equal, if not superior, to AChE histochemistry as a confirmative finding in HSCR (Guinard-Samuel et al. 2009; Kapur et al. 2009). Moreover, calretinin immunostaining can be performed on a paraffin section from a biopsy used for H&E analysis, thereby eliminating any need for additional biopsies or frozen sections.

Considerable variation exists in the approaches taken by clinicians and pathologists to diagnosis of HSCR. In particular, the number of biopsies, number and thickness of sections, and use of AChE or calretinin staining differ between groups (Qualman et al. 1999). The approach used by the author is shown in Fig. 7.9 and incorporates calretinin immunohistochemistry as part of a routine procedure. AChE histochemistry can be substituted for calretinin immunohistochemistry but requires an additional frozen biopsy. The author believes that routine use of either ancillary method is advisable to ensure that technical and interpretative proficiency are maintained. However, others reserved AChE histochemistry or calretinin immunohistochemistry for cases when a biopsy is suboptimal (usually too little submucosa) and neither ganglion cells nor hypertrophic nerves are visualized in H&E-stained paraffin sections. Regardless, a strong HSCR-type AChE-staining pattern or complete lack of calretinin-immunoreactive nerves in the mucosa supports the diagnosis of HSCR. A normal or equivocal ancillary test result must be factored with clinical data (e.g., barium enema, family history, clinical severity), in order to decide whether to re-biopsy or manage conservatively. As with so many aspects of surgical pathology, the most important constant in HSCR diagnosis is clear communication between the clinician and pathologist, particularly about equivocal results.

Many surgical approaches to HSCR are currently employed with a trend toward one-stage procedures that are transanal. In some instances, diagnosis based on suction rectal biopsy is followed by a two-stage procedure that begins with placement of an ostomy proximal to the aganglionic segment. Intraoperative seromuscular biopsies are important to determine that ganglion cells are present at the level where the ostomy or anastomosis will be placed. During such surgery, aganglionic gut may not be biopsied, a commitment to resection of at least the distal rectum having been decided based on the preoperative biopsy diagnosis. The transition to ganglionic bowel is located by analysis of seromuscular or full-thickness biopsies examined by intraoperative frozen sections. Generally, this is accomplished by sequential biopsies, from distal to proximal, until ganglion cells are identified.

Seromuscular biopsies should be a minimum of 5 mm in length and extend for a depth of 3–5 mm, so as to include the longitudinal and most of the circular layers of the muscularis propria. Proper orientation of the biopsy for frozen sections greatly facilitates sampling and identification of ganglion cells. The goal is to cut perpendicular to the serosal surface, thereby visualizing both the muscle layers and their interface in the histological sections. Ten sections are usually sufficient to confirm/exclude aganglionosis. Recognition of ganglion cells is generally not difficult, although inflammation sometimes obscures their cytological features (Fig. 7.10). For unknown reasons, in many instances, eosinophils predominate in infiltrates of the myenteric plexus, both in the aganglionic gut and more proximally (Fig. 7.11) (Lowichik and Weinberg 1997).

Although perfectly controlled investigations have not been performed, the consensus from several published studies is that resection for HSCR should encompass the aganglionic bowel and any neuroanatomically abnormal transition zone, such that an ostomy or anastomosis is created with “normal” intestine (Langer 2004; Boman et al. 2007; Lawal et al. 2011; Coe et al. 2012). Intraoperative microscopic examination of a frozen section of the full circumference (“donut”) of the proximal resection margin is one way to reduce the likelihood of a transition zone pull-through. Features of transition zone to be excluded include aganglionosis or severe hypoganglionosis of large segments of the circumference and hypertrophic nerves in the submucosal or myenteric plexuses, as described below.

The pathologist’s goals in analyzing resected aganglionic gut from an HSCR patient are to confirm the diagnosis of HSCR, establish the length of the aganglionic segment, and assess the integrity of the nervous system at the proximal end of the resection. Confirmation that the distal gut is aganglionic is straightforward (Fig. 7.12). If the proximal margin was examined intraoperatively by frozen sections, the findings should be confirmed by examining paraffin sections of the residual frozen. In addition, a permanent section of a second full-circumference tissue sample immediately adjacent to the proximal margin is also useful to confirm the frozen section findings with a well-oriented and well-fixed tissue that lacks any freezing artifacts. The approximate length of the aganglionic segment can be established by sampling a longitudinal strip of the resected bowel. Although not absolutely necessary, the author favors mapping the transition zone by sampling multiple areas along the length of the resected segment to document the presence/absence of submucosal and myenteric ganglia (Fig. 7.12). Because the interface between aganglionic and ganglionic gut is often irregular (Gherardi 1960; White and Langer 2000), it is prudent to map this area with closely spaced transverse sections, particularly if the transition is close to the proximal resection margin (Kapur 2009). Construction of a decent map may require repeated sampling sessions.

Examination of a full-circumference section from the proximal margin of the resection to exclude neuroanatomical defects is the most challenging and arguably the most important aspect of the process. In principle, the genetic etiologies that produce distal aganglionosis may have more subtle effects on the number, distribution, circuitry, and/or differentiation of proximal neurons (Amiel et al. 2008). Certainly, most HSCR patients harbor a transition zone of variable length (Fig. 7.13), in which the density of myenteric ganglia is obviously less than in normal gut (Gherardi 1960; White and Langer 2000; Boman et al. 2007). However, mild-to-moderate changes in neuronal density are extremely difficult to diagnose by routine analysis and yet may correlate with continued HSCR-like symptoms postoperatively (Swaminathan and Kapur 2010).

In H&E-stained sections, the most frequently cited morphological features of transition zone are hypoganglionosis (oligoganglionosis) and hypertrophic nerves. In the distal transition zone, oligoganglionosis manifests as large portions of the circumference devoid of ganglion cells. Overlapping defects in the distribution of submucosal ganglion cells are common, but the correlation is not perfect. Regardless, priority is given to the distribution of myenteric ganglion cells because the normal distribution of submucosal ganglia is so sporadic and overt submucosal aganglionosis/hypoganglionosis seldom extends much farther rostrally than myenteric hypoganglionosis. In the proximal transition zone, a milder pattern of hypoganglionosis is characterized by a relatively normal circumferential distribution of ganglia, but small ganglia that consist of one or two ganglion cells with minimal neuropil (Fig. 7.14).

Hypertrophic submucosal and myenteric nerves, similar to those observed in aganglionic bowel, are another histopathological feature of the transition zone (Levitt et al. 2010). Such nerves can extend for several centimeters proximal to the aganglionic segment. These nerves share light and ultrastructural properties with extraenteric or serosal nerves, which arise from neuronal cell bodies outside the gut wall. Some, especially those in the submucosa, are thicker (>40 μm) than normal enteric nerves (Fig. 7.15). They appear more compact than normal intrinsic nerves of the enteric plexuses and, unlike the latter, are surrounded by perineurium. The perineural cells expressing Glut1 can be readily identified by immunostaining for this antigen (Kakita et al. 2000) (Fig. 7.15). The functional significance of hypertrophic nerves in ganglionic bowel has yet to be determined, but enlarged nerves are prevalent proximal to anastomoses in some patients with persistent postoperative obstructive symptoms (Coe et al. 2012). To avoid potential dysmotility associated with hypertrophic nerves, removal of transition zone with hypertrophic innervation has been recommended by at least one group (Lawal et al. 2011; Coe et al. 2012).

In addition to hypoganglionosis, submucosal hyperganglionosis (intestinal neuronal dysplasia (IND) type B, discussed later in this chapter) has been reported in the proximal gut of HSCR patients (Puri et al. 1977; Meier-Ruge 1992; Moore et al. 1994). This entity is discussed more fully later in this chapter. Some investigators have gone as far as to suggest that serial biopsies of colon proximal to the aganglionic zone should be obtained to exclude IND before a pull-through procedure (Meyrat et al. 2001; Meyrat and Laurini 2003). However, insufficient compelling data exists to suggest that IND-like changes in HSCR either predict a poor outcome or should be managed any differently (Hanimann et al. 1992; Banani et al. 1996; Schmittenbecher et al. 1999; Haricharan et al. 2008; Coe et al. 2012).

It is important to be aware of two rare forms of congenital aganglionosis that deviate from the classic pattern, in which the distal rectum and uninterrupted contiguous bowel are devoid of nerve cell bodies (Kapur et al. 1995). In the intestinal tracts of persons with “segmental” (“zonal”) aganglionosis, ganglion cells are present in the distal rectum but are absent from a proximal segment of gut (Fig. 7.16). In contrast, “skip areas” are ganglion-cell-containing segments of large intestine, flanked proximally and distally by aganglionic gut (Fig. 7.16).

Segmental aganglionosis is considered to be an acquired lesion (disruption) that results when ganglion cells (or their precursors) in a fully colonized segment of gut die due to ischemic, viral, immunologic, or other types of injury (Yunis et al. 1983; Smith et al. 1997). The aganglionic segment can occur in small or large intestine. In some cases, a specific etiology is suggested by history (e.g., necrotizing enterocolitis), serological evidence for antineuronal antibodies, or other pathological findings (e.g., viral cytopathy). Alternatively, it has been suggested that segmental aganglionosis might result from failure of vagal and sacral crest cells to converge in the gut wall (Vaos 1989). At the time this hypothesis was introduced, it was less certain that sacral crest cells naturally adopt an enteric neural fate. Given recent evidence that a subset of colonic neurons derive normally from the sacral crest, the proposal is more tenable (Burns et al. 2000; Wang et al. 2011).

Skip areas are located in the large intestine and flanked by aganglionic areas that invariably include the distal rectum and appendix plus variable lengths of contiguous large and small intestine (Kapur et al. 1995). In a sense, a skip area is a ganglion-cell-containing segment that interrupts what otherwise would be an example of total colonic aganglionosis. A small skip area may involve only a small portion of the colonic circumference. In contrast, a large skip area can extend from the cecal region into the transverse or left colon. Pathologists and surgeons must be cognizant of skip areas and not use biopsies of the appendix as a means to diagnose total colonic aganglionosis since relatively large skip areas can be present in which ganglion cells exist. In at least one patient, the skip area was recognized, preserved, and used to establish a functional anastomosis between small intestine and anus (Martin et al. 1979).

Ultrashort-segment HSCR is a controversial entity that has been defined differently by various investigators (Neilson and Yazbeck 1990; Ballard 1996; Meier-Ruge et al. 2004). Initially, the term “ultrashort-segment HSCR” was reserved to describe patients with clinical and radiological findings similar to those of HSCR, but with ganglion cells in their rectal biopsies (Davidson and Bauer 1958). The underlying assumption was that an extremely short aganglionic zone in the distal rectum, inferior to the submucosal biopsy site, was responsible for their symptoms. Others suggested that such patients had hypoganglionosis, which was unrecognized with contemporary pathological studies (reviewed by Ballard 1996), but convincing documentation of clinically significant distal hypoganglionosis is extremely difficult since ganglion cells are normally sparse or absent in the terminal 2–3 cm of the rectum (Fig. 7.17) (Aldridge and Campbell 1968).

The author believes that “ultrashort-segment HSCR” should be reserved for patients with aganglionic distal rectal tissue and one or more additional histological feature of HSCR including abundant hypertrophic submucosal nerves and/or an unequivocal HSCR pattern of AChE histochemical or calretinin immunohistochemical staining (Kapur 2009). Other terms (e.g., internal sphincter achalasia) should be used for patients with clinical and manometric findings similar to HSCR, but with incomplete histological findings to support the latter diagnosis (Doodnath and Puri 2009). Conditions that mimic ultrashort-segment HSCR physiologically are likely to be heterogeneous given that regulation of anal sphincter tone is complex and is influenced by both the central and peripheral nervous systems (Stebbing 1998). Heightened sphincter tone could be caused by psychogenic, myogenic, or neurogenic etiologies. A major stimulus for sphincter relaxation is nitric oxide (NO) release by efferent nerve fibers in the smooth muscle (Buntzen et al. 1996). Reduced nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase activity (nitric oxide synthase), a marker for NO-producing nerve fibers, has been observed in the internal sphincter of patients with anal achalasia (Hirakawa et al. 1995; Moore et al. 1996). In some cases, the symptoms resolve after sphincter myotomy or Clostridium botulinum toxin injection (Krebs and Acuna 1994; Moore et al. 1996; Minkes and Langer 2000).

Chagas disease, the most widely recognized infectious etiology of pseudo-obstruction, is caused by the intracellular parasite Trypanosoma cruzi, which is endemic throughout much of Central and South America. The organism is carried in the alimentary tracts of several insect vectors and is transmitted via their fecal matter to many different mammals. The organism is also transmitted between humans congenitally or by blood transfusion. Infection is divided into acute and chronic phases (Koberle 1968). The acute phase occurs within weeks of initial infection and manifests in many patients as myocarditis and/or encephalitis. Acute Chagas disease usually has no gastrointestinal symptoms, although histopathology of the gut reveals inflammation in the smooth muscle and around and within ganglia. Organisms (amastigotes) may be visible in smooth muscle cells (Fig. 7.18) but are not usually present in ganglion cells.

Obstructive symptoms and distension of the gut in Chagas disease occur in regions with markedly deficient myenteric neurons and glial cells (Todd et al. 1969; da Silveira et al. 2007b). Ganglion cells appear to be lost primarily late in the acute phase and progressively during the chronic phase, during which time lymphocytic ganglionitis is present. Most patients do not develop pseudo-obstruction or megacolon until many years after the acute illness. Loss of ganglion cells is attributed to either an immune-mediated process or a neurotoxin, but not neuronal infection per se. With time, significant thickening of the muscularis propria due to smooth muscle cell hyperplasia occurs in the hypoganglionic gut. Eventually, these areas may be profoundly distended and virtually aperistaltic. In addition, a contributor to dysmotility may be autoantibodies that bind to and agonize muscarinic acetylcholine receptors expressed on enteric smooth muscle cells (Sterin-Borda et al. 2001).

An estimated eight million persons in Central and South America and 300,000 person in the United States are infected with T. cruzi (Rassi et al. 2010). Over their lifetimes, 10–15 % of infected individuals will develop chronic digestive disease. Several studies suggest that variants of genes which encode tumor necrosis factors and other immunoregulatory molecules influence susceptibility to Chagas disease (Campelo et al. 2007; Alvarado Arnez et al. 2011). However, no predominant genetic risk factor has been identified.

Enteric dysmotility with megaesophagus and/or megarectum is a component of chronic disease. Megacolon frequently targets portions of the rectosigmoid and left colon and produces obstipation, abdominal distension, and occasionally obstruction.

Barium enema demonstrates marked dilatation of affected colon. Segmental distension of the sigmoid region is most frequent.

Marked segmental colonic distension, smooth muscle hypertrophy, and hypoganglionosis are hallmarks of Chagasic megacolon. Organisms, which may be visible histologically in smooth muscle cells during acute infection (Fig. 7.18), are not present. However, a lymphocyte-rich infiltrate may surround or infiltrate myenteric and submucosal ganglia and nerves, including nerves that ramify through the muscularis propria (da Silveira et al. 2007b). The inflammatory cell population includes CD20-positive, CD3-positive, natural killer, and cytotoxic lymphocytes. Lymphocytic ganglionitis is present in patients with or without megacolon, but the proportion of natural killer and cytotoxic lymphocytes is significantly greater in distended colonic specimens. The densities of myenteric ganglion cells, glial cells, and peripherin-positive innervation are all greatly reduced with megacolon (Adad et al. 2001; da Silveira et al. 2007b).

In early stages, medical management of Chagasic constipation is possible using laxatives or other agents. As the disease progresses, surgical resection of affected colon may be necessary. Antitrypanosomal agents are advised for patients with acute disease, but their value in patients with chronic disease is debated (Rassi et al. 2010).

Neuronal intranuclear inclusion disease (NIID) is a hereditary disorder that affects the central and peripheral nervous systems. It is a neurodegenerative disorder characterized by progressive neuronal loss. Although the mechanisms responsible for cell loss are not known, analogies have been made to forms of spinal cerebellar ataxia and other hereditary neurodegenerative disorders in which intranuclear inclusions are found (Takahashi-Fujigasaki 2003). Many of the latter conditions result from expansions of trinucleotide (polyglutamine) repeat sequences in a specific gene. The gene product is one of several proteins that form an intranuclear inclusion, but it is unclear whether their accumulation has a toxic, protective, or bystander role in neuronal degeneration (Takahashi et al. 2000; Pountney et al. 2008).

Despite the fact that most cases of NIID are sporadic, several well-documented familial examples suggest an autosomal dominant disorder due to mutations in an as yet unknown gene.

The clinical presentation of NIID is variable and may include any of a plethora of neurological symptoms including parkinsonism, cerebellar ataxia, chorea, dystonia, nystagmus, pyramidal tract signs, seizures, mental retardation, autonomic dysfunction, and peripheral neuropathy (Josephs 2011). Age of onset differs, but onset in childhood is most frequent. Intestinal dysmotility may be a minor component or may dominate the clinical picture (Schuffler et al. 1978; Barnett et al. 1992; El-Rifai et al. 2006).

Insufficient information exists to describe any characteristic radiological features of intestinal disease in these patients, although dilatation of proximal bowel (esophagus, stomach, and/or duodenum) has been the most consistent finding. “Nonpropulsive contractions of a dilated esophagus and small intestine” were observed in two adult siblings (Schuffler et al. 1978). The small bowel series from a neonate with NIID and pseudo-obstruction showed dilatation of the duodenum (El-Rifai et al. 2006).

The characteristic histopathological feature is an eosinophilic circular intranuclear inclusion in myenteric and submucosal ganglion cells (Fig. 7.19). Such inclusions are often present simultaneously in neuronal nuclei in other parts of the peripheral nervous system, spinal cord, and brain, although functional deficits may not be evident in some of these sites (Erdohazi 1974; Malandrini et al. 1996; Goebel 1999). As the disease progresses, neuronal loss is typical and oligoganglionosis of both myenteric and submucosal plexuses may be severe.

At least two families have been described in which intestinal pseudo-obstruction and intranuclear inclusions in enteric ganglion cells were prominent findings (Schuffler et al. 1978; Barnett et al. 1992). In each instance, the affected individuals were adults, but they exhibited signs and symptoms of pseudo-obstruction since childhood. Evidence for central nervous system involvement was clinically detected in all patients (e.g., ataxia, dementia, abnormal electroretinograms) and was confirmed pathologically in the brother and sister reported by Schuffler et al. (1978). The inclusions are generally larger (5–6 μm in maximal diameter) and more eosinophilic than neuronal nucleoli and surrounded by a clear halo (Fig. 7.19). Ultrastructurally, they are composed of tightly packed electron-dense filaments. They do not stain with Alcian Blue, Congo red, periodic acid-Schiff, Sudan black B, or methyl green. They are immunoreactive with antibodies specific for SUMO1, ubiquitin, and a variety of other nonspecific components (Pountney et al. 2008). Similar inclusions are found in autonomic and sensory ganglion cells, as well as in neurons and astrocytes of the brain and spinal cord. In the siblings reported by Schuffler et al., a third of all enteric ganglion cells contained inclusions and quantitative neuronal counts demonstrated a marked reduction in the density of ganglion cells throughout the gut. Analogous quantitative data was not presented for the family reported by Barnett et al. (1992). However, “a significant reduction of neurons” was specifically noted in biopsies from one patient.

Diagnosis of NIID from skin biopsies is possible (Sone et al. 2011). Nuclear inclusions with identical antigenic and electron microscopic features to those found in neurons are found in a subset of sweat gland cells, fibroblasts, and adipocytes.

Treatment is symptom based and does not prevent progression.

Intestinal pseudo-obstruction due to immune-mediated inflammation of myenteric +/− submucosal ganglia is a well-recognized complication of neoplasia (Lennon et al. 1991; Gerl et al. 1992; Chu et al. 1993; Condom et al. 1993; Anderson et al. 1996; De Giorgio et al. 2003). Neuroendocrine tumors including carcinoids and pulmonary small cell carcinoma appear particularly prone to associated enteric ganglionitis, and a 16-year-old girl was reported with ganglionitis and pseudo-obstruction that were diagnosed 1.5 years after a paravertebral ganglioneuroblastoma was successfully removed (Schobinger-Clement et al. 1999). The offensive tumor may be small and occult. Therefore, diagnosis of enteric ganglionitis necessitates a comprehensive search for neoplasia elsewhere.

Histologically, the inflammatory infiltrates are dominated by lymphocytes, predominantly T cells, plasma cells, and small numbers of histiocytes. Inflammation is usually confined to the ganglia and nerve plexuses but can affect any or all parts of the alimentary canal. The density of inflammatory cells is highly variable. Severe inflammation may obscure normal ganglionic cell types. Often, ganglion cells show degenerative features including hyperchromasia, nuclear pyknosis, or cellular dissolution. Non-enteric autonomic and sensory ganglia may be affected similarly. Even with successful treatment of the neoplasm, progressive neuronal loss and gliosis usually occur.

The pathogenesis of paraneoplastic ganglionitis is not conclusively established, but almost certainly has an immune basis. Reasonable titers of neuron-specific antibodies, particularly those that recognize nuclear antigens in CNS neurons (ANNA-1, anti-Hu), are generally present in the patient’s serum. These same antibodies bind to nuclear and/or cytoplasmic antigens expressed by enteric neurons. Presumably, lymphocytic infiltration of enteric ganglia results because of cross-reactivity with antigens produced by the neoplastic cells (De Giorgio et al. 2003). Immunosuppression may be helpful if it can be initiated before significant ganglion cell loss has occurred.

The clinical presentation and histopathological features of idiopathic ganglionitis are virtually identical to paraneoplastic ganglionitis, except no neoplasm is identifiable (Briellmann et al. 1996; De Giorgio et al. 2000). As in paraneoplastic ganglionitis, antineuronal antibodies can usually be documented in the patient’s serum and progressive neuronal loss to aganglionosis has been reported (Smith et al. 1997).