Abstract
Neoplasms of the anogenital region usually have a broad differential diagnosis including metastatic and primary malignancies, with overlapping morphology and immunohistochemistry and thus requiring an extensive work-up. We present a case of a 70-year-old female with a 3-year history of an asymptomatic vulvar lesion and no other significant past medical history. Physical examination revealed a 9-mm flesh colored papule on the left labia. Clinical work-up also revealed a 1.4 cm right upper lobe lung mass. Biopsy of the vulvar lesion showed a basaloid cell proliferation in the dermis that extended into the subcutis. The proliferation consisted of lobular pattern of tubular and ductal structures in a background of fibrous stroma with central area of degeneration. While the superficial component of this proliferation appeared circumscribed and contained ductal structures with retained myoepithelial layer, the deeper part showed infiltrative growth and atypical cytomorphology. Both components were positive for EMA, CEA and CK8/18, and negative for CD117, p63, GCDFP-15, ER, PR, Her2, TTF-1 and Napsin A. The histologic notion of a composite benign and malignant growth was supported by SMA and CK5 that showed intact myoepithelial layer around the benign component but was lost in the deeper infiltrative areas. Notably, CK5 was diffusely positive in the infiltrative component and a higher proliferation index with Ki-67 stain. A diagnosis of apocrine carcinoma arising in a tubular apocrine adenoma was made. Metastatic carcinoma, especially from breast, and apocrine carcinoma (both p63 negative) are important differentials when encountering neoplastic glandular proliferation of anogenital region and differentiation requires clinicopathologic correlation. The morphologic features in our case were of apocrine ductal carcinoma that have not been previously reported to arise in long-standing benign counterparts, making this an interesting finding.
Financial Disclosure:
No current or relevant financial relationships exist.