Infantile rhabdomyofibrosarcoma: A potentially underdiagnosed aggressive tumor
A 2 years and 6-month-old male presented with a large soft-tissue mass in the left axillary region. The mass was painless and had slowly progressed in size over 10 months. He did not have any constitutional symptoms. On examination, the mass measured 15 cm × 15 cm. It was firm, bosselated, non-tender, free from the overlying skin, but adherent to the underlying tissue.\nComputed tomography (CT) scan revealed large homogenously enhancing mass without any calcification or underlying bone involvement. During excision surgery, the mass was found to be well encapsulated and arising from the serratous anterior and adherent to the pectoralis, scapula, and subscapularis. Histopathology revealed a tumor composed of spindle cells, arranged in fascicles and whorls, having pale eosinophilic cytoplasm, hyperchromatic pleomorphic oval and spindle nuclei, with 8-10 mitoses/10 high power fields []. There was no evidence of hemorrhage or necrosis. The morphological diagnosis was reported as IFS. Histopathology review and immunohistochemistry revealed diagnosis of IRMFS with strong positivity for desmin, smooth muscle actin and vimentin, and negativity for myogenin-D1, myoglobin and cluster of differentiation (CD) 34 []. There was no evidence of metastases to the lung, bones or bone marrow. In view of an aggressive nature of the tumor, he underwent wide local excision and received adjuvant chemotherapy with weekly vincristine with 3 weekly actinomycin-D and cyclophosphamide for 1 year as per rhabdomyosarcoma (RMS) protocol. CT scan after treatment completion did not reveal any tumor. At the time of submission of this article, he was in remission about 2 years after completion of chemotherapy.