A patient presents with lymphedema and a mass in their breast after chest radiation in childhood. What is the likely diagnosis?

• A. Angiosarcoma
• B. Kaposi's sarcoma
• C. Fibroadenoma
• D. Breast carcinoma

Answer: (A)

Radiation-associated angiosarcoma should be considered when a patient develops a vascular-appearing breast lesion in the setting of prior chest irradiation, especially with surrounding lymphedema. The combination of long-standing lymphedema and a new mass in an irradiated breast is a classic pattern for a malignant transformation of endothelial cells into an angiosarcoma. These tumors arise years after radiation and tend to be aggressive, often requiring wide excision or further treatment due to their propensity for local recurrence and metastasis. Histologically, they show malignant endothelial proliferation forming irregular vascular channels, with strong endothelial marker staining (for example CD31).

Kaposi sarcoma would suggest HHV-8 infection in the setting of immunocompromise and typically has different clinical context. Fibroadenoma is a benign proliferative lesion common in younger patients and not linked to prior radiation or lymphedema. Breast carcinoma can occur after radiation, but in a child the history of chest radiation with lymphedema makes angiosarcoma the more likely diagnosis and explanation for these findings.