RESUMO
Pigmented actinic keratosis (PAK) is an uncommon variant of actinic keratosis that can mimic different pigmented lesions, which may be benign or malignant. The diagnosis of PAK is often challenging because of overlapping features with lentigo maligna melanoma (LMM). Clinically, lesions of both conditions almost look similar; the diagnoses must be established histologically and with the help of immunostaining whenever needed. The distinction between a large PAK and LMM is important because their prognosis and management differ. We present a 75-year-old female with annular brown-to-black-colored maculo-plaque on forehead having clinical suspicious of melanocytic malignancy; which was diagnosed with a PAK on biopsy with help of histopathology and confirmed with Melan A/MART‑1 immunostaining.
RESUMO
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.