[Palmar filiform parakeratotic hyperkeratosis without underlying malignancy]

Filiform hyperkeratosis (FH) is a rare entity clinically characterized by keratotic spicules on the palms, soles or other areas of the body surface. Its association with several diseases, including neoplasms, has been extensively discussed but currently it is not considered a well-defined paraneoplastic disorder. We report a 72-year-old patient that referred lesions on both palms of three months duration. The rest of the body surface did not show similar lesions. Complementary exams did not reveal any abnormal findings. The histopathological exam showed parakeratotic columns with a slightly decreased granular layer and a mild dermal inflammatory infiltrate. In the last years different terms have been employed to refer to these hyperkeratotic lesions contributing to the lack of clarity that currently persists. Although FH might be classified close to the clinical spectrum of porokeratoses, it presents particular clinical and histological findings that allow it to be considered a separate entity. We report a new case of this rare disorder with exclusive palmar involvement in a patient without underlying malignancy and review the main characteristics of similar cases reported in the literature. Despite the obscure association between this entity and neoplasms, the majority of authors deem it necessary to rule out underlying diseases.