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Other dermatoses

Radiation associated

Reviewer: Mowafak Hamodat MB.CH.B, MSc., FRCPC, Eastern Health, St. Johns (Canada) (see Reviewers page)
Revised: 2 August 2011, last major update August 2011
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.

Clinical features

● Radiation causes various benign vascular proliferations including benign lymphangiomatous papules (the lymphatic counterpart of telangiectases due to destruction/obstruction of lymphatic drainage), atypical vascular lesions mimicking benign lymphangioendothelioma, patch stage Kaposiís sarcoma and well differentiated angiosarcoma (involves subcutaneous tissue, marked cytologic atypia, piling up of endothelial cells, Ki-67+)
● Occurs 3-20 years after radiation exposure
● May be acute or chronic and follows therapeutic or accidental overexposure
● Often women treated for breast cancer
● Redness, swelling, hair loss and blistering
● Morbiliform, papular, annular and bullous lesions
● An erythema multiforme-like dermatosis is rare complication of radiotherapy
● Chronic radiation may present with acne vulgaris, ringworm, atrophy and scaling, variable hypo- and hyper pigmentation, telangiectasias and often alopecia

Case reports

● 49 year old woman with lesions secondary to breast cancer radiation (Am J Surg Pathol 2002;26:1372)

Clinical description

● Papules, small vesicles or erythematous plaques on irradiated field

Micro description

● Epidermis may be necrotic and accompanied by both spongiosis and intracellular edema
● Hydropic degeneration of basal layer of epidermis and sometimes sub-epidermal vesiculation
● Dermis is edematous and may show fibrin deposition; also dermal macrophages, eosinophils, plasma cells and lymphocytes
● In early stages, vascular thrombosis is a feature
Chronic radiation dermatitis: epidermis shows hyperkeratosis and may show foci of parakeratosis, acanthosis or atrophy with attenuation of ridge pattern; may be spongiosis or basal cell liquefactive changes, cytologic atypia and dyskeratosis; dense fibrosis and elastosis in dermis, with fibrinous excaudate; blood vessels often thickened and fibrointimal hyperplasia is present; telangiectatic vessels may be present; loss of appendages, particularly hair follicles; associated with epidermal dysplasia, squamous or basal cell carcinoma
● Bizarre fibroblasts, with abundant polydendritic basophilic cytoplasm and large hyperchromatic or vesicular nuclei may suggest a neoplastic process; also seen in chronic lichen simplex, pressure ulcer and pleomorphic fibroma
Post UV-B radiation: damaged keratinocytes (sunburn cells), intercellular edema and exocytosis; dermal changes include endothelial cell swelling and perivenular edema with a predominantly mononuclear intradermal chronic inflammatory cell infiltrate; also elastosis in fair skinned individuals
Post UV-A radiation: keratinocyte swelling, vacuolation accompanied by intercellular edema and diminished numbers of Langerhans cells, but no sunburn cells; dermis has mixed infiltrate of neutrophils, lymphocytes and occasionally basophils and eosinophils; also endothelial swelling
Benign lymphangiomatous papules/plaques: superficial dermal involvement by irregularly dilated vascular spaces in branching and anastomosing pattern; vessels have thin walls and lymphatic appearance, with single layer of discontinuous flattened endothelial cells; also numerous small stromal papillary formations lined by endothelial cells that project into lumina
Atypical vascular proliferations mimicking benign lymphangioma or patch stage Kaposiís sarcoma: poorly circumscribed and focally infiltrating, irregular jagged vascular spaces involving entire dermis; lined by inconspicuous endothelial cells; variable dissection of dermal collagen bundles

Positive stains

● CD31 stains vessels

Negative stains

● CD34, smooth muscle actin

Differential diagnosis

Acute GVHD

End of Skin-nontumor > Other dermatoses > Radiation associated

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