Large, linear pigmentation anomaly: an unusual dyspigmentation case.

Segmental pigmentation anomalies can be further divided into segmental pigmentation disorder (SPD) complex and café-au-lait macules (CALMs). Both are congenital skin conditions characterized by hyper- or hypopigmentation. Segmental pigmentation disorder is a rare entity, whereas CALMs are common skin lesions that may be associated with various genetic conditions, especially when several are present and the patient has other indicators of a genetic abnormality. When the CALM is segmental, segmental neurofibromatosis (type V) may be considered in the differential diagnosis. Herein we present a 48-year-old woman with a history of malignant melanoma who presented with a large, linear, hyperpigmented patch on her shoulder and arm, present since around birth. The differential diagnosis consisted of CALM versus hypermelanosis (a subtype of SPD). Given a family history of a similar lesion, in addition to a personal and family history of melanoma and internal cancers, a hereditary cancer panel was completed demonstrating genetic variance of uncertain significance. This case brings attention to a rare dyspigmentation disorder and questions a possible association with melanoma.