Punch biopsy revealed collagen extravasation consistent with acquired reactive perforating collagenosis, an uncommon acquired disease that is seen in patients with longstanding renal disease or diabetes mellitus. The patient’s history of end-stage renal disease, paired with the eruptive nature of the pink papules with central firm plugs, pointed to the diagnosis.
The differential diagnosis for lesions like these includes prurigo nodularis and eruptive keratoacanthomas. Prurigo nodules would itch but likely lack a central plug. Eruptive keratoacanthomas would have a central keratinaceous plug but would be less likely to itch. A biopsy can help distinguish these entities.
Reactive perforating collagenosis can affect up to 10% of hemodialysis patients. It also can be associated with human immunodeficiency virus, hyperparathyroidism, hypothyroidism, liver disease, and sclerosing cholangitis. One theory of the etiology is that underlying disease causes skin itching and the subsequent trauma from scratching causes reactivity.
The work-up consists of a punch biopsy of the entire lesion or central plug. A biopsy limited to the edge of the lesion, or one that is shallow, may fail to connect altered dermal collagen with its follicular elimination and be misread as dermatitis.
Lesions often resolve spontaneously, but disease can be widespread. Topical steroids and antihistamines may reduce itching. Narrowband UVB, topical or systemic retinoids, tetracyclines, and cryotherapy all have had reported success. Narrowband UVB is especially helpful for uremic pruritus and, if available, may be the treatment of choice.
This patient was treated with topical steroids, oral cetirizine 10 mg/d, and cryotherapy to the most stubborn lesions. Over 3 months, the number of lesions and severity of symptoms improved. She continued hemodialysis and awaits a renal transplant.
Photos and text for Photo Rounds Friday courtesy of Jonathan Karnes, MD (copyright retained). Dr. Karnes is the medical director of MDFMR Dermatology Services, Augusta, ME.