Keratoacanthoma is a malignant tumor that is rarely located in the subungual region, but which has a tendency to recur. Spontaneous regression of these lesions in the nail apparatus region almost never occurs, and a differential diagnosis with other neoplasias, particularly squamous cell carcinoma, is essential. The authors present the case of a man with a diagnosis of subungual keratoacanthoma, which responded well to surgical treatment and had a favorable development.

Keywords: NAILS; KERATOACANTHOMA; FINGER FALANGES.

INTRODUCTION: Seborrheic keratosis (SK) has the typical pigmented dermoscopy features such as fissures and ridges, fat fingers, and cerebriform patterns. Here we describe a case where pigmented columns (PC) were visualized on SK’s dermoscopy associated with a squamous cell carcinoma (SCC). Case presentation: We report a case of a lesion whose dermoscopy showed PC. Histopathological report showed well-differentiated SCC and associated SK. Discussion: The PC was visualized in an area of dendritic melanocytes in the epidermis, correlating with the pigmented SK component of the lesion. To our knowledge, this is the first time PC is described in SK´s dermoscopy.

Keywords: Carcinoma squamous cell; Dermoscopy; Skin neoplasms.

INTRODUCTION: Temporal triangular alopecia (TTA) is a nonscarring, noninflammatory, permanent form of alopecia with an unknown etiology, often misdiagnosed as other types of alopecia.
CASE REPORT: A 27-year-old woman presented with triangular patches of alopecia in the temporal regions, resembling male pattern alopecia. Dermoscopy revealed normal follicular openings. Histopathological analysis showed only vellus follicles, with no telogen or terminal follicles, intact sebaceous glands, and no inflammatory infiltrate.
DISCUSSION: Dermoscopy is a valuable diagnostic tool, and histopathology may be performed in selected cases. There is no definitive treatment for TTA. Management options include topical minoxidil, hair transplantation, or surgical excision.

Keywords: Alopecia; Temporal Distribution; Hair Diseases.