We report a case of pigmented Bowen's disease in the periungual region treated with Mohs micrographic surgery. Bowen's disease is a squamous cell carcinoma in situ. Although it is a common condition, the pigmented form is rarer, with periungual localization being even more uncommon. Pigmented Bowen's disease presents clinically as a non-uniform, desquamous or verrucous brownish lesion, and it is often confused with other diseases (pigmented actinic keratosis, seborrheic keratosis, melanoma, basal cell carcinoma, nevus). Dermoscopy is of great diagnostic and therapeutic value and is important in the evaluation of recurrence.

Keywords: BOWEN'S DISEASE; CARCINOMA, SQUAMOUS CELL; DERMOSCOPY

Pilomatrixoma is a benign tumor with differentiation to the hair matrix that can affect different regions of the skin. We report the case of a patient with an unusual presentation on the scalp, with warning signs for the possibility of a malignant variant of the tumor. We emphasize the importance of documenting atypical conditions that may permeate the practice of dermatologists and the need to rule out malignancies in the face of a change in the pattern of skin lesions, exulcerations, and bleeding, among other signs. The role of histopathology is fundamental for diagnostic definition and therapeutic management.

Keywords: Pilomatrixoma; Skin neoplasms; Hair diseases