Translucent Papules on a Mastectomy Scar

A 66-year-old woman with a history of breast cancer treated by right mastectomy and adjuvant radiotherapy in 2014 presented in 2020 with a 3-month history of asymptomatic skin lesions over the mastectomy scar. Her medical history included diabetes mellitus, hypertension and hypothyroidism. On examination, the scar area showed multiple clustered papules and translucent vesicles, skin-coloured to slightly erythematous, measuring 1–5 mm in diameter (Figure 1). No lymphedema or systemic symptoms were present, and a skin biopsy was performed for histopathological evaluation (Figures 2 and 3). Lymphangioma circumscriptum (LC) is a late cutaneous complication of post-radiotherapy tissue injury. A skin biopsy revealed dilated, anastomosing lymphatic channels lined by flattened endothelial cells within the superficial dermis, embedded in a lymphoplasmacytic infiltrate (Figures 2 and 3). These findings were consistent with a benign lymphatic proliferation. The patient was treated with 3 weekly sessions of cryotherapy using liquid nitrogen, each involving two 20 s freeze–thaw cycles per lesion. A marked clinical improvement was observed, with significant lesion clearance and minimal residual hypopigmentation (Figure 4). Unfortunately, the patient was lost to follow-up thereafter. These findings align with the diagnosis of LC, which represents a benign lymphatic malformation characterized by clusters of vesicles and papules, often mistaken for other vascular or neoplastic lesions. It is considered part of the broader spectrum of lymphatic anomalies and can occur as a congenital or acquired condition. In adults, it may be acquired secondary to trauma, infection, surgery or radiotherapy [1, 2]. Post-radiotherapy LC is rare but increasingly recognized, particularly in female patients treated for breast cancer. It typically affects previously irradiated skin, most commonly involving the head, neck, chest, axilla, extremities and oral mucosa [3]. Clinically, LC appears as clusters of dome-shaped, translucent vesicles, sometimes filled with clear or blood-tinged fluid. Although lesions are often asymptomatic, they may cause pruritus or discomfort, and rupture may lead to secondary infections. Benign lymphangiomatous papules should also be considered in the differential diagnosis [4]. Histopathology is essential for diagnosis and to rule out angiosarcoma or atypical vascular proliferations. LC is characterized by dilated lymphatic vessels lined by bland endothelial cells and a surrounding lymphoid infiltrate, typically lacking cytologic atypia [5]. Immunohistochemistry may assist in distinguishing LC from malignant vascular tumours when features are equivocal [6]. The pathogenesis in post-radiotherapy cases involves radiation-induced fibrosis and obstruction of dermal lymphatics, leading to fluid accumulation, increased pressure and eventual dilation of superficial lymphatic vessels. Cryotherapy is a suitable treatment for localized lesions, causing targeted damage to abnormal lymphatics. Other options include laser therapy, sclerotherapy and surgical excision [7]. In our case, cryotherapy yielded significant improvement with minimal adverse effects. However, recurrence remains possible, and long-term monitoring is advised. This case highlights the need for dermatologists and oncologists to consider LC in the differential diagnosis of vesiculopapular eruptions within irradiated skin, particularly in breast cancer survivors. Prompt recognition and biopsy are essential to avoid confusion with post-radiation angiosarcoma, a potentially fatal malignancy [8]. Hind Ouerghi: conceptualization, clinical data collection, writing original draft. Rym Kort and Sirine Boumaiza: clinical examination, manuscript review. Imen Helal and Ehsen Ben Brahim: histological analysis and interpretation. Rym Kort and Achraf Chadli Debbiche: supervision, critical review, final approval of manuscript. The authors have nothing to report. All patients in this manuscript have given written informed consent for participation in the study and the use of their deidentified, anonymized, aggregated data and their case details (including photographs) for publication. The authors declare no conflicts of interest. The data that support the findings of this study are available from the corresponding author upon reasonable request.