A 36-year-old woman presented with a 4-month history of progressive, ulcerating plaques on both legs. One month prior to the onset of her rash, she noted bilateral swelling and decreased range of motion of her hands and feet.
The physical examination confirmed these findings and also revealed bilateral pitting edema of lower limbs. Her cutaneous examination revealed multiple indurated plaques with central ulceration on both legs (Figure 1(a)). There was no palpable purpura nor livedo reticularis. Coincidentally, she was also noted to have multiple yellowish papules diffusely scattered on the posterior neck (Figure 2(a)). These lesions were present since childhood. Her family history was unremarkable, and she denied any cardiac or ophthalmologic symptoms.
The patient did note polyarthralgia of her hands and ankles, and tenderness of the right Achilles tendon. She also noted paresthesia of her feet. A musculoskeletal (MSK) ultrasound of her hands, wrists, ankles, and feet showed no synovitis. X-ray imaging of the affected joints showed no erosions.
Her past medical history is significant for intellectual disability and a seizure disorder, both sequelae of an episode of meningitis as a child. Her medications at the time of presentation included levetiracetam, dilaudid, levonorgestrel-releasing intrauterine system, and acetaminophen. Her medications were long-standing, and there were no recent changes.
Her laboratory investigations included a normal complete blood count, normal mean corpuscular volume, normal renal function, normal liver profile, normal coagulation profile, and normal urine analysis. Her antinuclear antibodies, extractable nuclear antigen antibodies, lupus anticoagulant antibodies, and antineutrophil cytoplasmic antibodies (ANCA) serologies were negative. Hepatitis B, Hepatitis C, and HIV serologies were negative, and QuantiFERON-TB Gold was negative. Computerized tomography (CT) of the chest, and CT angiogram of the abdomen, and pelvis were unremarkable.
A biopsy at the border of the ulcer revealed a necrotizing medium vessel arteritis present in the dermis most suspicious of PAN (Figure 1(b)). Furthermore, she was seen by rheumatology who found she had no signs of systemic vasculitis particularly given the normal CT angiogram and MSK ultrasound showing no synovitis. Her presentation was consistent with limited or cutaneous PAN, and thus she was started on oral prednisone with the addition of celecoxib. She initially responded well to prednisone with almost complete resolution of her pretibial lesions. However, upon tapering the prednisone, her lesions recurred and she has since been maintained on hydroxychloroquine and methotrexate with excellent control.
In addition, her neck lesions were suspicious PXE, and thus one of the papules was biopsied. The biopsy showed clumped elastic fibers in the mid and deep reticular dermis suggestive of PXE. Von Kossa stain highlighted the clumped elastic fibers (Figure 2(b)).
Given the suspicion of PXE, she underwent cardiac, gastroenterological, and ophthalmologic evaluations which were within normal limit. Genetic testing for mutations associated with PXE was normal including an absence of ABCC6, ENPP1, and GGCX mutations. Furthermore, genetic testing for CECR1 mutations, which has been reported with PAN, was also normal.   The patient also has a normal array comparative genomic hybridization (CGH). Thus, the cutaneous findings were most in keeping with PXE-like phenotype.