Sebaceous carcinoma of skin expressing KIT and PDGFRA

Abstract

Only a little is known about expressions of KIT (CD117) and platelet-derived growth factor-alpha (PDGFRA) in sebaceous carcinoma of skin; recently one report showed expression of KIT in 12/13 (92.3%) in sebaceous tumors. No reports of PDGFRA in sebaceous tumors are present. An 82-year-old woman presented a face tumor. Physical examination revealed a polypoid tumor measuring 0.8 cm × 0.7 cm × 0.7 cm with reddish ulcerations in cheek skin. A biopsy was diagnosed as basal cell carcinoma (BCC) with sebaceous differentiation by the pathologist. Further excision of the tumor with wide margins was performed. Histologically, the tumor was polypoid and located in dermis. The epidermis showed ulceration. The tumor was composed of solid nests of atypical cells showing invasive features into dermis. The margins were negative for tumor cells, and no lymphovascular invasion were seen. Numerous islands of bubbly sebaceous atypical cells were seen within solid carcinoma cells with hyperchromasia and nucleoli. Numerous mitotic figures including atypical ones were seen. Focal areas show trichilemmal keratinization. Histochemically, no mucins, argyrophil cells, or argentaffin cells were seen. Immunihistochemicallly, tumor cells were positive for cytokeratin (CK) AE1/3, CK 34BE12, CK5, CK6, CK14, p63, KIT, PDGFRA, MET, ErbB2, p53 and Ki-67 (labeling index = 82%). The tumor cells were negative for CK CAM5.2, CK7, CK8, CK18, CK19, synaptophysin, chromogranin, NSE, NCAM, S100 protein, vimentin, -smooth muscle actin, CD34, D31, HMB45, MUC1, MUC2, MUC5AC, and MUC6. The author diagnosed the tumor as sebaceous carcinoma. The patient is now well and has no tumor 18 months after the operation.