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A Painful Firm Plaque on the Midback of a 53-Year-Old Woman: Answer.

ANSWER Fluoroscopy-Induced Chronic Radiation Dermatitis. The clinical appearance of an ulcerated plaque overlying the scapula in concert with the histologic appearance is the characteristic of fluoroscopy-induced chronic radiation dermatitis (FICRD). The biopsy reveals diffuse dermal sclerosis with enlarged pleomorphic and stellate-shaped fibroblasts. In addition, there is a loss of adnexal structures with retained “naked” arrector pili muscles (Fig. 2). Although the histologic findings suggest a diagnosis of chronic radiation dermatitis, the patient had no history of breast and lung carcinomas and reported no radiation therapy at this site. On further review of the medical records, a history of 2 cardiac catheterization procedures for coronary atherosclerosis, 7 and 9 years ago, was noted. The histologic findings in conjunction with a clinical history of fluoroscopy exposure during cardiac catheterization led to a final diagnosis of FICRD. The typical clinical presentation of FICRD includes dermal atrophy, persistent erythema, and sometimes ulceration, in close proximity to the area of radiation exposure during fluoroscopy procedure, most commonly the back, scapula, or infra-axillary region.1,2 The histological features of FICRD include ulceration, prominent telangiectasia, dermal sclerosis, and atypical stellate fibroblasts.2 There is a loss of the pilosebaceous structures with retention of the arrector pili muscles and atrophy of the eccrine glands. Morphea shares some of the histologic features of radiation dermatitis, namely, sclerotic collagen bundles and epidermal atrophy; however, the presence of ulceration, loss of pilosebaceous structures, thickened and hyalinized blood vessel walls, and lack of a lymphoplasmacytic infiltrate favor FICRD or radiation dermatitis.1,3 In contrast to FICRD, deep thermal injury causes a scar with complete destruction of the pilosebaceous structures, arrector pili, and the eccrine structures.4 Recognizing the pathogenesis of FICRD is helpful in distinguishing it from other entities. Chronic radiation injury commonly occurs over months to years after exposure with a cumulative dose threshold of 1000 rad (10 Gy). Although radiation doses delivered during fluoroscopic procedures are typically below the threshold necessary for the development of chronic radiation dermatitis, repeated or prolonged procedures may induce FICRD.5,6 Patients with connective tissue disorders,7,8 HIV infection,9 basal cell nevus syndrome, lupus erythematosus,10–12 and genetic disorders such as xeroderma pigmentosa13,14 are more prone to developing chronic radiation dermatitis. Obesity and diabetes have been associated with higher incidence of FICRD.15 A variety of complications can arise from FICRD. The affected skin is generally very sensitive to trauma, which may lead to persistent ulceration.16 A subset of patients with FICRD can develop squamous cell carcinoma or basal cell carcinoma.17–19 Squamous cell carcinoma arising in postradiation skin may behave more aggressively with a higher risk of metastasis.20 Postradiation angiosarcoma and postradiation atypical vascular lesions may also be diagnostic considerations in light of the clinical presentation and history of radiation therapy. Postradiation angiosarcoma is an aggressive tumor with potential for metastasis, whereas postradiation atypical vascular lesion is a benign radiation-associated vascular proliferation.21–23 Clinically, these lesions appear as blue to purple papules, violaceous plaques, nodules, erythematous macules on the skin near the radiated area, occasionally presenting with ulceration, edema, or a palpable mass.24–27 Although these entities are important diagnostic considerations, our case does not demonstrate a primary atypical proliferation composed of dilated or interconnected anastomosing blood vessels.24,28 In conclusion, FICRD can be a diagnostic challenge when the complete clinical history is not offered or solicited. Therefore, it remains prudent to include FICRD within the differential diagnosis when confronted with a sclerotic or ulcerated plaque of unclear pathogenesis on the back, scapula, or infra-axillary region.