Muehrcke's lines (Leukonychia striata) due to transretinoic acid therapy for acute promyelocytic leukemia.

Transverse leukonychia (Leukonychia striata or Muehrcke's lines) has been described with the use of several drugs in oncology, mainly chemotherapeutic agents. This condition is thought to represent an abnormality of the vascular nail bed. As the diagnosis is clinical and the condition is self-limited, referral to other specialists is usually not required. We report the first case of transverse leukonychia related to the use of transretinoic acid for acute promyelocytic leukemia. Physician awareness of transverse leukonychia is important in order to reassure the patients and avoid unnecessary (and often not inexpensive) diagnostic work-up.