Pigmented Squamous Cell Carcinoma Arising from Pigmented Actinic Keratosis

ABSTRACT

Pigmented squamous cell carcinoma is a very rare malignant, pigmented, epidermal tumor. The rarity of pigmented squamous cell carcinomas may reflect in part their misdiagnosis as other pigmented neoplasms, particularly malignant melanoma. To our knowledge, only five cases have been reported in literature. We recently experienced a case of pigmented squamous cell carcinoma arising from pigmented actinic keratosis in a 77 years old female. Physical examination showed a 0.8 0.6 cm, smooth, dark brown pigmented patch with irregular but sharply defined borders located on the upper left chest. The biopsy specimen showed histologic findings of pigmented actinic keratosis with abundant melanin pigments, which became pigmented squamous cell carcinoma. Most of pigments in the squamous cell carcinoma were contained within the melanocytes along with the neoplastic squamous cells.