Teaching Case

A 75-year-old woman presented with a recent mild red-purple discoloration on her left breast, without experiencing pain or itchiness. Eight years prior, she had been diagnosed with invasive ductal carcinoma (cT2N0M0). After undergoing neoadjuvant chemo- and hormonal therapy, she had a tumorectomy, followed by adjuvant radiation therapy.

The mammography (Figures 1a-1b) showed a clear band of progressive cutaneous thickening compared to the older images (Figure 1c). This was confirmed with the ultrasound (Figure 2). The cutaneous thickening was most profound below the red-purple discolouration peri-areolar in the upper medial quadrant. The known scar after tumorectomy in the lower medial quadrant showed further shrinkage. No other new lesions were observed in the left breast. The MRI displayed a thick diffuse cutaneous hypo-intense band on the T1 (Figure 3a) and T2 (Figure 3b). The post-contrast images showed several nodular-enhancing lesions in the skin (Figure 3c and Figure 4). The largest was located under the discolouration. No suspicious lesions were found in the tumorectomy scar or elsewhere in the breast tissue. A specimen was taken with a cutaneous punch biopsy for pathologic analysis.

Angiosarcoma originates from endothelial cells and is fortunately very rare, accounting for less than 1% of malignant breast tumours. However, it is highly aggressive. Primary angiosarcoma typically affects women aged 30-40 and arises within breast tissue, often presenting as large masses and variable skin discolouration. Secondary forms are either radiation-induced or due to chronic post-operative lymphedema (Stewart-Treves syndrome). The disease usually occurs 5-7 years after radiotherapy, but cases have been reported from 1 to 41 years post-treatment. Since secondary angiosarcoma appears later, patients tend to be older (70-80 years). The incidence of radiation-induced angiosarcoma has increased, likely due to breast-conserving surgery and adjuvant radiotherapy [1, 2].

Secondary angiosarcoma typically affects the (sub)cutaneous tissue, sparing the remaining breast tissue. Intraparenchymal involvement is seen in about 25% of cases. Initial clinical presentation often involves red or purple skin discolouration or cutaneous thickening (plaques), resembling ecchymosis. Only a small number of cases present as a lump, leading to delayed diagnosis [2].

Post-radiation dermatitis with dermal thickening and architectural distortions can be expected after breast radiotherapy, which should gradually decrease over time. New or increasing cutaneous thickening on mammography or ultrasound should alert the radiologist to consider mastitis, disease recurrence, or inflammatory breast cancer. Secondary angiosarcoma should be considered in cases with primarily skin involvement and/or skin discolouration, especially in patients with long disease-free intervals after radiotherapy. Further investigation with MRI and biopsy is warranted [2].

MRI is better at demonstrating the extent of the disease compared to mammography and ultrasound. Secondary angiosarcoma presents as T2 hyperintense (sub)cutaneous thickening with or without hypointense nodular lesions on MRI. Post-contrast images show diffuse or nodular strong enhancement with a dynamic type 2 or 3 curve [2, 3].

Secondary angiosarcoma has a poor prognosis, with a 5-year survival rate of 10-54% and high local and distant recurrence rates. Treatment involves resection of all radiated skin tissue followed by chemotherapy [2].

Written informed patient consent for publication has been obtained.