Diagnosis: Fluoroscopy-induced radiation dermatitis
Our patient had radiation dermatitis, an uncommon but important potential complication of fluoroscopic procedures. The condition can be subdivided into acute, chronic, and subacute forms, with the subacute form representing a mixture of the clinical pictures of the acute and chronic forms.
Acute radiation dermatitis presents as waves of erythema two to nine days after exposure to ionizing radiation at a threshold dose of 200-800 rad (2-8 Gy). The erythema may be accompanied by edema, vesiculation, erosion, ulceration, or pain. Eventually, the skin may darken and desquamate. The radiation injury can take several weeks to several months to subside; in some cases, the skin may never return to normal.
Chronic radiation dermatitis has a cumulative dose threshold of 1,000 rad (10 Gy). Onset may be several months to years or decades following exposure. The characteristic dermatologic effects include telangiectasia, atrophy with loss of cutaneous appendages, erythema, and pigmentary changes.
The most common locations of fluoroscopy-associated radiation dermatitis following cardiac procedures include the right or left scapular and subscapular areas, the right lateral trunk below the axilla, the midback, and the right anterolateral chest. Risk is greatest in patients who have had multiple procedures over a lifetime, a prolonged procedure, and percutaneous coronary intervention in which the radiation was focused only on the vessels with stenosis.
Further, the type of machinery used, the facility where the procedure was done, and the proficiency of the person performing the angiography may all impact the dose of radiation for a particular procedure.
The diagnosis of radiation dermatitis is often made clinically; biopsy may be required only to rule out such other disorders as erysipelas or inflammatory metastases (carcinoma erysipeloides). In acute radiation dermatitis, biopsy will show either ulceration or subepidermal blister, superficial dermal edema, degeneration of dermal connective tissue, and vascular dilation. Chronic radiation dermatitis is characterized histologically by epidermal hyperplasia or atrophy, pallor and necrosis of keratinocytes, telangiectatic blood vessels, degeneration and hyalinization of the dermis, and decreased adnexal structures. The diagnosis of subacute radiation dermatitis rests on seeing a lichenoid tissue reaction histologically.
Acute radiation dermatitis may be treated with topical steroids, such as triamcinolone acetonide, and emollients, such as vaseline or hydrophor, to reduce pain and erythema. There is no specific therapy for the chronic or subacute forms. Protection from sunlight and regular skin examinations are recommended, as patients with chronic radiation dermatitis are at increased risk of basal and squamous cell carcinomas.
Our patient had mild relief with topical triamcinolone acetonide. He is followed closely with regular skin examinations.