Alveolar Soft-part Sarcoma on the Abdominal Wall in an Adult: A Rare Presentation with Cytological and Histological Correlation

Sir,

We report a case of a male patient who presented with a painless swelling in the abdomen noticed 6 months back, with sudden increase in size over the past 3 months. On examination, there was a firm swelling of size 8 cm × 6 cm in the left hypochondrium, in the intramuscular plane. Contrast-enhanced computed tomography revealed a well-defined solid mass lesion with central hypodensity and heterogeneously intense postcontrast enhancement within the rectus abdominis muscle in the supraumbilical region. Imaging features suggested the possibility of a neurogenic tumor. Fine-needle aspiration revealed loose aggregate and dispersed large cells with eccentric nuclei, prominent nucleoli, and abundant granular cytoplasm [Figure 1a] and [b]. Many bare nuclei were seen. With the differential diagnosis of alveolar soft-part sarcoma (ASPS) and granular cell tumor, a wide excision was done to remove the tumor.

Figure 1: (a) Smear showing loose clusters of large cells with abundant granular cytoplasm (H and E, ×10). (b) High-power image showing frayed cytoplasm and large nuclei with nucleoli (H and E, ×40). (c) histology showing large cells in nests with delicate septa (H and E, ×10); inset showing granular cytoplasm, large nuclei, and prominent nucleoli (H and E, ×40). (d) Intracytoplasmic rod-like crystals (Periodic acid–Schiff with diastase, ×40)

The specimen showed a circumscribed soft reddish-brown tumor of size 6.2 cm × 5.7 cm × 3.3 cm. Histology revealed large polygonal cells in nests and organoid pattern with delicate septa. The cells had abundant eosinophilic granular cytoplasm, eccentric round nuclei, and prominent nucleoli [Figure 1c]. Nuclear atypia, tumor giant cells, multinucleation, and extensive lymphovascular emboli were present. Periodic acid–Schiff (PAS) and PAS with diastase revealed tumor cells with intracellular crystalline material [Figure 1d]. The tumor sections were subjected to a panel of immunohistochemical markers including vimentin, desmin, pancytokeratin, chromogranin, CD10, myogenin, NSE, S-100, and Ki-67. The tumor cells were positive to vimentin [Figure 2a] and desmin [Figure 2b]. The other immunohistochemical markers were negative. These morphological and immunohistochemical features favored the diagnosis of ASPS.

Figure 2: (a) Tumor cells showing positivity to vimentin (×40). (b) Tumor cells with desmin positivity (×40)

Publikationsverlauf

Artikel online veröffentlicht:
03. Juni 2021

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