Title : Amelanotic acral malignant melanoma misdiagnosed as poroma
Abstract:
A 72-year-old male presented with a red nodule on left planta for two months. Physical examination revealed a pea sized red nodule on left planta, with clean and dry surface, and tenderness. The patient was clinically diagnosed as poroma. Histopathology of skin lesion showed atrophy of epidermis, and tumor cells diffused from dermis to subdermis, part of which arranged in nests, with invasion of vasculature and nerves. The tumor cells were composed with rich plasma and atypical nuclear, and infiltration of a few lymphocytes could also be seen. No ulcers. Morphologically consistent with malignant melanoma, nodular type. Breslow thickness was about 13.6mm, Clark grade 5, and mitosis was 1/mm2. Tumor cells were found in the lateral and basal margins. Immunohistochemistry showed HMB45(+), Sox10(+), S100(+), Vimentin(-), CK(-), SMA(-), EMA(-), Ki67 about 5%(+). The diagnosis of acral malignant melanoma was established.
Audience Take Away Notes:
- Reported a rare case of amelanotic acral malignant melanoma
- The lesion was a red nodule on left planta, with clean and dry surface, which was quite similar to poroma
- This case reminds us to remain highly vigilant about amelanotic acral malignant melanoma
