Metaplastic breast carcinoma with melanocytic differentiation

Area of Science:

• Oncology
• Pathology
• Dermatology

Background:

• Metaplastic carcinoma of the breast (MCB) is a rare breast malignancy (<1% of invasive breast carcinomas).
• MCB is characterized by a mixture of adenocarcinoma with mesenchymal elements (spindle, squamous, chondroid, or bone-forming cells).
• Metaplastic breast carcinoma with melanocytic differentiation is exceptionally rare, with only seven prior cases documented.

Observation:

• A 38-year-old woman presented with a suspicious nodular breast mass detected via ultrasound.
• Initial diagnosis of the resected tumor was a collision tumor: invasive ductal carcinoma and metastatic melanoma.
• Histological and immunohistochemical analyses were crucial for accurate diagnosis.

Findings:

• The case was re-evaluated and confirmed as metaplastic carcinoma with melanocytic differentiation.
• The patient received quadrantectomy, chemotherapy, and radiotherapy.
• A 6-year follow-up revealed no local recurrence or distant metastases, indicating successful treatment.

Implications:

• This case expands the understanding of rare metaplastic breast carcinoma subtypes.
• It underscores the importance of thorough histopathological and immunohistochemical evaluation for accurate diagnosis.
• The successful treatment outcome suggests that standard multimodal therapies may be effective for this rare variant.