Synovial sarcoma: A case report of first presentation at penoscrotal junction

Abstract

Synovial sarcoma is a rare malignant tumour that arises from mesenchymal origin. This case is about synovial sarcoma in unusual place, the scrotum and penile shaft. A 36-year-old man presented with a tender penoscrotal mass for 5 years. The patient underwent surgical resection of the mass. Histopathology revealed cellular spindle cell tumour arranged into interlacing fascicle, Immunohistochemistry analysis revealed a positive TLE-1, CD99, B-cell lymphoma 2 (BLC2), Focal cytokeratin and focal epithelial membrane antigen (EMA). In our case, the patient was aggressively treated with two surgical resections and still progressed and metastasized and continued progressing even after different chemotherapy regimens.

1 Introduction

Synovial sarcoma is a tumour that accounts for 8 %–10 % of soft tissue sarcomas, it is a rare malignancy from mesenchymal origin. The classification of synovial sarcoma depends on morphology and topography. Most commonly, synovial sarcoma affects the extremities, but it can affect any anatomical part of the body. It is usually found in children and early adulthood. Synovial sarcoma is reported to be prognostically better in younger age. It has been reported in different unusual places in the body, including inguinal region, retroperitoneum, internal organs and mediastinum. ^, This case represents a new unusual location of synovial sarcoma; scrotum and penile shaft.

2 Case presentation

February 2020, a 36-year-old with no significant past medical history presented with 5 years history of left sided penoscrotal mass. He has no lower urinary tract symptoms. No History of trauma or infections and he denied any history of weight loss, anorexia or fever. On examination, there is a smooth surface, tender cystic lesion around 20 mm ∗ 20 mm attached to the left side of the bulbar urethra at the penoscrotal junction, it was deep without any skin tethering and not related to the left spermatic cord and it was partially mobile.

Doppler ultrasonography showed a well-defined hypoechoic mass measuring 2.7 ∗ 3.1 ∗ 2.0 cm with significantly increased vascularity at the left of penoscrotal junction. Pelvis Magnetic resonance imaging revealed a mass in the left inferolateral side of the base of the penis with a clear fat plane, which is isointense to the testes in the T2 weighted imaging, T1 weighted imaging and Diffusion-weighted imaging and it was connected to the vas deferens, no lymphadenopathy was noted ( Fig. 1 ). Alpha fetoprotein and beta-human chronic gonadotrophin levels were all in the normal range. Given the results of workup and the pain experienced by the patient, a decision was made to proceed with surgical removal of the mass for both diagnostic and therapeutic purposes. During surgery, a mass was seen in the left posterolateral of the scrotum and it was resected completely and sent for histopathology ( Fig. 2 ).

Histopathology of the mass showed cellular spindle cell tumour arranged into interlacing fascicle, the cells have spindle to oval vesicular nuclei with evenly dispersed chromatin and inconspicuous nucleoli ( Fig. 3 ). The tumour showed high mitotic activity reaching up to 3/High-power field. Immunohistochemistry analysis was consistent with synovial sarcoma, revealing a positive TLE-1, CD99, B-cell lymphoma 2 (BLC2), Focal cytokeratin and focal epithelial membrane antigen (EMA) ( Fig. 4 ). The material was sent for Fluorescence in situ hybridization (FISH) and reported a rearrangement of the SS18 gene at 18q11.2 which has been observed in synovial sarcomas. The mass margins were difficult to be assessed by histopathology as the sample had fragmented margins.