Microcystic adnexal carcinoma of the lower lip: a report of a case and review of the literature

Abstract

<h3>Background</h3> Microcystic adnexal carcinoma is a relatively uncommon skin appendage tumor which shows evidence of both pilar and sweat gland differentiation. This locally aggressive and deeply infiltrative malignancy shows a strong predilection for the head and neck region, particularly the midfacial area, and displays a high rate of recurrence if not completely excised. Clinically, these lesions present as firm subcutaneous nodules that may mimic scars or other benign lesions. Characteristic microscopic features include islands of small basaloid keratinocytes with a bland cytologic appearance, keratin-filled cysts, eccrine ductal structures, deeply infiltrative growth, and perineural invasion, all within a background of desmoplastic stroma. The histologic differential diagnosis includes such neoplasms as syringoma and desmoplastic trichoepithelioma. <h3>Objective</h3> The purpose of this study is to describe the incidence and clinical and histologic features of microcystic adnexal carcinoma and to present a case involving the lower lip. <h3>Case report</h3> We report a case of microcystic adnexal carcinoma presenting in the lower lip of a 71-year-old male. The lesion presented as a persistent scar-like subcutaneous mass of the lower lip without evidence of a skin or mucosal surface lesion. The patient was treated by surgical excision and remains disease-free 21 months after excision. <h3>Conclusion</h3> Although microcystic adnexal carcinoma is an uncommon skin appendage tumor, it shows a very strong predilection for the head and neck region. In addition, these lesions are very locally aggressive. The clinical and histologic presentations often mimic other, often benign, lesions, and it is imperative that both the clinician and pathologist be aware of its features so that prompt diagnosis and adequate treatment occurs.