Post irradiation cutaneous angiosarcoma of the breast misdiagnosed for radiation induced dermatitis

Clinical History

The patient had breast conservation surgery for invasive breast carcinoma six years ago. Post surgery she received radiotherapy and chemotherapy. Four years later she presented with an erythematous macular lesion of the ipsilateral breast which was diagnosed as chronic radiation induced dermatitis.However, this lesion progressed to an elevated papulonodular congested lesion.

Imaging Findings

She presented with an erythematous macular lesion on her breast in 2007, however, the mammograms during the two-year disease course did not reveal any significant abnormality besides thickening of the overlying skin which was interpreted as part of post radiation changes (Fig. 1 and 2). In April 2009 the erythematous lesion (Fig. 3) progressed to a nodule. Hence an excisional biopsy (Fig. 4) was performed. It revealed a spindle-celled lesion containing irregular ectatic blood vessels lined by atypical endothelial cells with intervening solid areas (Fig. 5) which were immunopositive for CD31 and CD34, confirming the vascular origin, leading to a diagnosis of cutaneous angiosarcoma of the breast. This was followed by a radical mastectomy in May 2009 which revealed associated intraparenchymal extension (Fig. 6). In July 2010, MDCT of chest and abdomen revealed lung and liver lesions which were confirmed as metastasis on biopsy (Fig. 7).

Discussion

Elshimali et al have suggested four criteria for diagnosis of post irradiation angiosarcoma which include history of radiation, tumor in the field of radiation or the adjacent skin, several years or later post radiation treatment and confirmation by biopsy and histology[1]. In women with breast cancer treated with radiotherapy the incidence of angiosarcoma is estimated to be 0.4%[2].
Mammograms in patients with secondary angiosarcoma may show only changes due to breast conservation and prior radiation therapy. Angiosarcoma associated skin thickening may be mistaken for post radiation skin changes on mammogram. However post radiation skin changes are most pronounced at 6 months post radiation treatment and these changes decrease in prominence with time. However in cases of parenchymal involvement, ill defined asymmetric masses may be seen on mammography. Similarly, skin changes due to radiation and angiosarcoma are difficult to differentiate on ultrasonography of the breast. Parenchymal lesions have non specific findings of heterogeneous areas with alteration of the normal tissue planes or superficial hypoechoic mass on ultrasound[3, 4]. Hence mammography and ultrasound scans are usually not helpful for diagnosis as noted in this case. However magnetic resonance imaging can be helpful in identifying the lesion and its extent. A heterogenous mass is usually seen on MRI, with low signal intensity on T1 weighted images and high signal intensity on T2 weighted images[5]. Low grade lesions show progressive enhancement whereas high grade lesions show rapid enhancement and washout on MRI[3].
Usually, there is at least a 5-year interval between breast irradiation and the appearance of the angiosarcoma, but some occur with a short latent period of 3 years[6]. Initial skin changes of angiosarcoma may be similar to the telangiectasia often seen as late sequelae of breast irradiation[7]. Increased attention must be given to a patient with skin alteration after radiotherapy. The lesions of angiosarcoma are difficult to diagnose sometimes, since they mimic radiation dermatitis and atypical vascular lesions. Biopsy of these areas must be done early in such patients as early diagnosis and surgery leads to improved outcomes in this otherwise aggressive tumor[8].
Due to the erythematous appearance of the lesion, a diagnosis of chronic radiation dermatitis was made. It was the transformation to a nodular congested appearance, that a biopsy was performed revealing cutaneous angiosarcoma with intraparenchymal extension and subsequent metastasis. If a more aggressive approach for evaluation of the erythematous lesion had been performed earlier, this may have led to a difference in the patient's management and prognosis.

Differential Diagnosis List

Final Diagnosis

Post irradiation cutaneous angiosarcoma of the breast with intraparenchymal extension

URL:	https://www.eurorad.org/case/9277
DOI:	10.1594/EURORAD/CASE.9277
ISSN:	1563-4086