Basal-Cell Carcinoma Occurring in Cutaneous Infundibular Cysts: Report of 2 Cases and Review of the Literature.

Cysts lined by stratified squamous epithelium indistinguishable from the epidermis, referred to as epidermoid cysts, epidermal inclusion cysts, and infundibular cysts, are the most common type of cyst occurring in the skin. They are invariably benign, and malignant neoplasms arising within the wall of such cysts are distinctly uncommon. Even basal-cell carcinoma, which is the most common cutaneous malignant neoplasm of the skin, has rarely been reported to occur in association with epidermoid cysts. The authors report their experience studying 2 patients with basal-cell carcinoma arising in association with an epidermoid cyst. These cases highlight the need to examine, histopathologically, tissue from this common and usually benign lesion. The authors also review the medical literature.

Biopsy diagnoses of clinically atypical pigmented lesions of the head and neck in adults.

A subset of facial melanoma in situ has histological features that overlap with those of "dysplastic" nevi. The authors evaluated this important diagnostic pitfall by assessing the frequency of melanoma as the final diagnosis in skin biopsies submitted over a 1-year period with a clinical impression of "atypical" or dysplastic nevus from the head or neck of adults. A total of 1998 biopsies met inclusion criteria. Final diagnoses included both melanocytic and nonmelanocytic processes. Clear trends were noted based on the age of the patient with benign nevi encompassing nearly 70% of specimens in patients aged 21-29 years and <10% in patients aged 70 years and above. The incidence of atypical nevi decreased with age (16% in 21-29 years, 3% in age 70+ years). Nineteen of the 180 (10%) atypical nevi in our series were located on the face (7, cheek; 6, forehead; 3, jawline; and 3, temple), a location not traditionally associated with atypical nevi. Facial atypical nevi were found in all age groups. Malignant melanoma accounted for 1.8% of all specimens increasing from 0% in the patients aged 21-29 years to 5% in patients aged 70 years and above. Caution is warranted when evaluating skin biopsies from sun-damaged skin of the head or neck of an older adult submitted with a clinical diagnosis of atypical nevus. However, the authors' findings suggest that atypical nevi with histological features of dysplastic nevi occur on the head and neck of adults, including elderly adults. The incidence of such lesions decreases with age as the incidence of melanoma increases, and careful clinicopathologic correlation is vital.