Regressed subungual melanoma simulating cellular blue nevus: managed with sentinel lymph node biopsy.

Background: Subungual melanoma, a not uncommon presentation of cutaneous melanoma in Asian populations, is easily overlooked as benign and thus is improperly treated.

Objective: To present two cases with clinical suspicion of subungual melanoma. Skin biopsies failed to demonstrate the diagnostic features of malignancy.

Methods: Lymphoscintigraphy and sentinel lymph node (SLN) biopsies were performed to determine regional lymph node status.

Results: Both hematoxylin-eosin and HMB45 staining revealed melanoma cells in the SLN of the patient. The second patient's SLN was negative for malignant cells, but her excised primary lesion showed extensive regressed melanoma.

Conclusion: Regression phenomena are not uncommon for subungual melanoma. An extention biopsy techniques are useful for determining nodal basin status in regressed subungual melanoma.