Abstract PS1-05-06: Breast Calciphylaxis in a Patient with ESRD and Prior Radiation - A Diagnostic and Therapeutic Challenge

Abstract Intro Calciphylaxis is commonly associated with CKD and results from calcium deposition in dermal and adipose vasculature1. Diagnosis is often challenging with lesions typically presenting on the lower extremities or abdomen; involvement of the breast is rare2. This case describes a patient with breast calciphylaxis requiring multi-specialty management. Case Presentation A 69-year-old female with a history of grade 3 ER+/PR+/HER2− right breast intraductal carcinoma, status post partial mastectomy, axillary dissection and right breast radiation, presented with progressive skin changes of the right breast. Prior systemic therapy included two cycles of cyclophosphamide and docetaxel (discontinued due to rectal bleeding requiring exploratory laparotomy and partial colectomy), hormonal therapy, and radiation. Medical history is also significant for ESRD on HD, CHF, and pulmonary hypertension. Patient was diagnosed with breast cancer in 2012 and had been under routine oncologic surveillance. In 2022, she noticed skin changes involving the right breast. Examination revealed skin thickening beneath the right breast, with satellite lesions and areas of hyperpigmentation and hypopigmentation. A biopsy of the right inframammary fold demonstrated dermal sclerosis and minute calcifications. These findings raised suspicion for radiation dermatitis versus calcium deposition. However, malignancy could not be definitively excluded, as the initial punch biopsy failed to penetrate the dense, plate-like nodules adequately. Screening mammograms remained negative since her initial diagnosis. The patient’s symptoms progressed with skin breakdown and drainage in areas of calcification. Laboratory studies remained consistent with ESRD but showed no acute uremic exacerbation. A recent breast ultrasound revealed multiple calcified areas, most prominent in the inferior breast, consistent with calcinosis cutis. The patient's pain and tenderness became severe enough to preclude further mammography. Treatment attempts included antifungal and barrier creams, calcium binders, and a trial of sodium thiosulfate, none of which provided significant relief. The patient was not a suitable candidate for calcium channel blockers or bisphosphonates. Surgical excision was deemed high-risk due to the extensive resection area required, with concerns regarding poor wound healing, dehiscence, and recurrence. The patient declined surgical intervention and opted for continued follow-up with dermatology and the wound care. A repeat biopsy, two years after the initial one, demonstrated dermal fibrosis, perivascular plasmocytic inflammation, and vascular ectasia, without evidence of malignancy. Discussion Calciphylaxis is a rare but often fatal condition, with wound-related infections contributing to mortality rates of up to 60% within one year 3. This case highlights the need for a high index of suspicion, particularly in patients with ESRD and lesions in uncommon locations such as the breast. Diagnosis can be difficult due to overlapping features with conditions like radiation dermatitis or recurrent malignancy and may require multiple biopsies. In this patient, differentials included calcinosis cutis, scleroderma, inflammatory breast cancer, and chronic radiation dermatitis. Classic calciphylaxis pathology findings include medial calcification of dermal arterioles, fibrointimal hyperplasia, microthrombi, and necrosis, demonstrating some overlap with pathology seen in this case. Although calciphylaxis is strongly associated with ESRD, most dialysis patients do not develop it. In this patient, the coexistence of malignancy, prior radiation, and ESRD may have played a synergistic role in disease development. Citation Format: N. S. Verma, R. Kannaiyan, K. Lathrop. Breast Calciphylaxis in a Patient with ESRD and Prior Radiation - A Diagnostic and Therapeutic Challenge [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS1-05-06.