Pyogenic Granuloma-like Amelanotic Melanoma of the Fingernail

Abstract

Amelanotic melanoma is an atypical melanoma that presents without pigmentation and can thus be misdiagnosed as benign neoplasm. Ungual trauma can induce amelanotic melanoma of the fingernail as well as pyogenic granuloma (PG). We present the case of a patient in his 60s with a PG-like lesion on his third nail plate that was preceded by ungual trauma one year ago. A shave biopsy revealed an ulcerated nodule composed of epitheloid cells with melanocytic atypia, extending 1.7 mm. Features were consistent with melanoma, confirmed with SOX10, S100, MART-1, and HMB45 immunostaining. This case demonstrates the integral role of histopathology and immunostaining in differentiating a benign PG from amelanotic melanoma, and thereby, preventing metastasis. We present this case to improve clinicians’ ability to recognize atypical melanomas and to emphasize the importance of biopsy in such cases to ensure timely treatment and patient outcomes.

Keywords

• pyoderma gangrenosum
• melanoma
• skin cancer
• amelanocytic melanoma
• dermatopathology
• medical dermatology