Pathology Quiz Case 1

Abstract

A 10-YEAR-OLD BOY PRESENTED WITH A 1-YEAR history of a painless submucosal mass in the left side of his tongue. The mass, which had gradually increased in size during the past months, made it difficult for him to protrude his tongue. He denied any pain or numbness. His medical and family histories were unremarkable. On physical examination, a linear indentation and only mild mucosal ulceration were noted. The tongue deviated to the left side on protrusion. There were no other cranial nerve deficits.The results of initial laboratory studies were within normal limits. Gadolinium-enhanced T1-weighted magnetic resonance images (MRIs) of the neck were obtained (Figure 1). Because the findings of fine-needle aspiration biopsy were inconclusive, an incisional biopsy was performed. A representative hematoxylin-eosinstained section is shown in Figure 2. Immunohistochemical stains were positive for cytokeratin (Figure 3), vimentin, epithelial membrane antigen, the MIC2 gene product CD99 (O13) (Figure 4) but negative for CD56, bcl-2 protein, common leukocyte antigen, CD34, CD117, actin, desmin, S100 protein, and the melanocyteassociated marker HMB-45.