Difficult Diagnosis in a Patient With Painful Subcutaneous Nodules

Arthur Kavanaugh, MD

Disclosures

June 03, 2002

Question

My patient is a 46-year-old white female with a several-month history of lower-extremity rashes, initially on the legs and now on the lower thighs. She has raised, bright red lesions of 3 mm to 5 mm in diameter that appear to have extravasation, because the lesions spread and age like a bruise. She has tender, several-centimeter-sized subcutaneous nodules which are not necessarily located under the cutaneous lesions. I have seen her on 1 occasion, yesterday, and biopsied a cutaneous, but not a subcutaneous lesion.

She has had multiple diagnoses from 4 different physicians, including erythema multiformae (I disagree). Evaluation has included a normal urinalysis, complete blood cell count, blood cultures, erythrocyte sedimentation rate of 18, and a chemistry screen showing electrolytes, liver function tests (LFTs), blood urea nitrogen (BUN), and creatinine within normal limits. She has been treated in the past with corticosteroids, azithromycin, cetirizine hydrochloride, hydroxyzine, and various narcotics. She does not have pruritis, just "severe" pain from the subcutaneous nodules.

I initially thought of Henoch-Schonlein due to the distribution of the lesions, but the normal lab findings do not support this (normal urinalysis, BUN, creatinine). I think she has a cutaneous vasculitis (the lesions are palpable) and erythema nodosum. C-reactive protein (CRP), perinuclear antineutrophil cytoplasmic (P-ANCA), antinuclear antibody (ANA), anti-DNA, anti-Sm, anti-RO, and anti-La antibodies, and antihistone and antiribonucleoprotein tests are pending. Biopsy results are also not yet available.

Do you have any thoughts or suggestions about this diagnosis?

Maaurice Strickland, MD

Response from Arthur Kavanaugh, MD

This certainly seems to be a complex case. With the presence of what sounds like painful subcutaneous nodules, I would agree that one should consider the diagnosis of septal panniculitis, such as erythema nodosum. Were any of the disorders commonly associated with erythema nodosum (eg, infections such as streptococcus, tuberculosis, or fungus; medications such as antibiotics; or other systemic inflammatory disorders) present in this case?

Forms of vasculitis such as this might be missed on superficial skin biopsy, and if the biopsy you obtained is unrevealing, I would suggest a full-thickness biopsy. Unfortunately, in cases such as these, serologic tests may be suggestive but not necessarily diagnostic. For example, ANA and related autoantibody testing would probably not be of too much value if the pretest probability of systemic lupus erythematosus was not high. Even the ANCA testing, whether positive or negative, may not help in the diagnosis of the conditions under consideration. While awaiting the results of the biopsy and other tests, it would certainly seem prudent to continue to assess for the presence of internal organ involvement (eg, renal, hepatic, bone marrow).

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