Delayed Diagnosis of Subungual Acral Lentiginous Melanoma

We report a 62-year-old, Hispanic male who presented to a rural medical provider who noted dark nail discoloration to the left thumb. Several weeks later, he presented to a rural emergency department with left thumb subungual hematoma and paronychia attributed to recent trauma. After evacuation and oral antibiotics, the provider discussed the prospect of melanoma given presence of longitudinal melanonychia and positive Hutchinson's sign. After 2.5 years, the patient re-presented to the same provider who noted increased pain and scarring of the left thumbnail. Referral to an orthopedic hand surgeon led to an MRI, which demonstrated findings most consistent with a benign glomus tumor. A left thumb mass excision and partial matrixectomy was performed with pathology revealing subungual amelanotic melanoma. The patient underwent left distal phalanx amputation of the thumb through the interphalangeal joint. Appropriate imaging and sentinel axillary lymph nodes were negative for metastasis. He continues to follow with medical oncology.