The curious incident of 3 melanomas and their possible origins—A case report and review of literature

BACKGROUND: We describe an unusual case of 2 intra-parenchymal breast melanomas with a concomitant subcutaneous melanoma in the ipsilateral upper limb and no definite primary lesion. CASE REPORT: Our patient is a 40-year-old Chinese female who presented with a breast lump in her left breast for which excision biopsy showed melanoma. A PET-CT revealed a second lesion in her breast. A left upper arm nodule with no overlying skin changes was also noted. She underwent a mastectomy and excision biopsy of the upper arm nodule. Histology showed that the second breast lesion was also a melanoma, while the arm nodule contained melanoma cells within a fibrous capsule. CONCLUSION: The presence of a melanoma in the breast should prompt a close and meticulous search for a primary lesion and potential signs of metastasis. Encapsulated subcutaneous nodules can be attributed to replaced lymph nodes or subcutaneous melanoma which can be either primary dermal melanoma or metastasis from an unknown primary.