Photo Rounds

Rash on lower legs and abdomen

A 26-year-old man presented to his family physician (FP) with a palpable rash on his lower legs and abdomen that had first appeared 5 days earlier. He denied any history of anything like this before and said he was not feeling ill. The rash did itch a bit, but there was no associated pain. The only medication the patient was taking was ibuprofen for occasional mild headaches. He did take some ibuprofen the week before this rash started.

What’s your diagnosis?


Rash on lower legs and abdomen

The FP suspected leukocytoclastic vasculitis (LCV) and, with the patient’s consent, performed a 4-mm punch biopsy on a well-developed lesion on the abdomen. Biopsies on the abdomen heal faster than the legs and may provide a better specimen to the pathologist. (See the Watch & Learn video on “Punch biopsy.”)

The biopsy confirmed the diagnosis of LCV. This is the most commonly seen form of small vessel vasculitis. LCV causes acute inflammation and necrosis of venules in the dermis. The term leukocytoclastic vasculitis describes the histologic pattern produced when leukocytes break apart into fragments. The purpura begins as asymptomatic localized areas of cutaneous hemorrhage that become palpable.

Discrete lesions are most commonly seen on the lower extremities, but they may occur on any dependent area. Small lesions may itch and be painful, but nodules, ulcers, and bullae may be more painful. Lesions appear in crops, last for 1 to 4 weeks, and may heal with residual scarring and hyperpigmentation. Patients may experience a single episode caused by a drug reaction or viral infection or have multiple episodes associated with rheumatologic diseases. LCV usually is self-limited and confined to the skin.

To make the diagnosis, look for the presence of 3 or more of the following:

  • age > 16 years;
  • use of a possible offending drug in temporal relation to the symptoms;
  • palpable purpura;
  • maculopapular rash; and
  • neutrophils around an arteriole or venule in a biopsy of a skin lesion.

In this case, the use of ibuprofen was the most likely precipitating event. Blood and urine tests did not show any renal or other organ system involvement. The patient was warned to not use ibuprofen in the future and that acetaminophen is a safer option for him. He was given topical triamcinolone cream 0.1% to apply twice daily for symptomatic relief. In this case, oral prednisone was not prescribed because the numerous potential adverse effects of prednisone outweighed the benefits. The vasculitis resolved in 4 weeks without any sequelae.

Photos and text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. This case was adapted from: Mayeaux EJ, Usatine R, Martin N, et al. Vasculitis. In: Usatine R, Smith M, Mayeaux EJ, et al, eds. Color Atlas and Synopsis of Family Medicine. 3rd ed. New York, NY: McGraw-Hill; 2019:1169-1173.

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