An Erythematous Plaque on the Left Breast of a 22-Year-Old Woman

A 22-year-old woman presented with an erythematous plaque on her left breast with a history of eight months. She was diagnosed with stage I infiltrating ductal carcinoma of the left breast (T1N0M0) and underwent breast-conserving surgery one year ago. After the operation, the patient received radiotherapy with a total dose of 50.0 Gy. Then, a red nodule appeared at the site of radiotherapy four months later and was surgically removed. However, the nodule recurred and gradually developed into a plaque, with no itching or pain. Physical examination revealed a well-defined erythematous plaque (10.0 cm × 4.0 cm) [Figure 1]. A skin biopsy specimen taken from the plaque on her left breast showed the proliferation of thin-walled, dilated venules in the superficial to mid dermis, without endothelial atypia [Figure 2a]. The sparse infiltration of inflammatory cells was observed. Immunohistochemistry revealed CD31 [Figure 2b] and CD34 positivity, while myelocytomatosis oncogene (MYC) negativity with a low proliferation index (Ki-67 < 3%).Figure 1: A well-defined erythematous plaque (10.0 cm × 4.0 cm) on the left breastFigure 2: (a) Histological results show the proliferation of thin-walled, irregularly branching venules in the dermis. (H and E, original magnification, ×100). (b) The immunohistochemical stain for CD31 is positive. (CD31, ×100)What is your diagnosis? Options: Kaposi sarcoma Cutaneous angiosarcoma Microvenular hemangioma Atypical vascular lesions. Answer: D. Atypical vascular lesions. Discussion Atypical vascular lesions (AVLs) are rare vascular proliferations induced by radiation, primarily affecting patients in their late 50s and presenting three to four years after radiation exposure.[1] The presumed aetiology of AVLs is the dilatation of superficial venules, secondary to lymphatic obstructions caused by radiation or surgery.[1] Clinical manifestations include solitary or multiple, well-circumscribed, red-bluish papules measuring less than 5 mm in diameter, with reported evolution into 20-mm-diameter plaques.[2] Histologically, examinations reveal dilated vascular channels lined by a single layer of endothelial cells without significant atypia, primarily located in the superficial or mid dermis and rarely extending into the deep dermis. Immunohistochemically, CD31 and CD34 are positive, while MYC displays negative staining patterns.[3] AVLs can be categorized into two types based on D2-40 positivity: lymphatic (D2-40 positive) vs vascular (D2-40 negative), with the vascular type potentially indicating a worse prognosis.[1] This case needs to be distinguished from Kaposi sarcoma (KS), cutaneous angiosarcoma (CAS), and microvenular hemangioma (MVH). KS, especially patch stage KS, is difficult to differentiate. Histological features including anomalous vascular spaces, infiltration of plasma cells, and promontory sign, combined with immunohistochemical positivity with HHV-8 and D2-40, contribute to the final diagnosis of KS.[4] CAS usually presents as a rapidly growing, purple-red nodule or plaque principally on the neck and head. Histopathology results reveal anastomotic network-like vascular channels and prominent atypical endothelial cells.[5] MVH typically presents as a proliferation of small, branch-like blood vessels, characterized by well-defined endothelial cells and distinctive vascular spaces.[6] The distinction between MVH and AVLs may be facilitated by considering the involvement of the entire dermis in MVH and the superficial dermis in AVLs, as well as the presence of chronic inflammation in AVLs and minimal lymphocytic inflammation in MVH.[6] While histopathology is valuable, in some cases, distinguishing between these entities may be challenging, necessitating additional clinical information and correlation. A history of radiotherapy in the affected area could suggest the possibility of radiation-induced AVLs. While AVLs are generally benign vascular tumours, regular follow-up is recommended. However, considering the overlaps with AS in clinical and histological features and rare reports of malignant transformation, complete removal is advisable for lesions exhibiting rapid growth.[3] Learning points Atypical vascular lesions (AVLs) are rare vascular proliferations induced by radiation. The biopsy is necessary for the final diagnosis of AVLs and contributes to excluding cutaneous angiosarcoma. Complete removal is advisable for lesions of AVLs exhibiting rapid growth. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship National High Level Hospital Clinical Research Funding 2022-PUMCH-A-161. Conflicts of interest There are no conflicts of interest.