Vasculitis Presenting as Calf Pain With Muscle-Limited Involvement

AUTHORS:
Aasia Ferdous, DO
Adena Health System, Chillicothe, Ohio

Kenneth Van Dyke, DO
Adena Health System, Chillicothe, Ohio

CITATION:
Ferdous A, Van Dyke K. Vasculitis presenting as calf pain with muscle-limited involvement. Consultant. 2020;60(2):62-63. doi:10.25270/con.2020.02.00009

A 37-year-old woman with no significant medical history was referred to the rheumatology clinic by her primary care provider for unexplained right calf pain and elevated inflammatory markers. She described the pain as sharp and stabbing, which worsened with activity. She also reported intermittent swelling of the lower part of the leg, which also was tender to the touch.

At her earlier primary care visit, findings of a review of systems were negative for any constitutional, cardiopulmonary, gastrointestinal, or neurological complaints. Vital signs were normal. Physical examination revealed a shiny and taut appearance to the right lower extremity with exquisite tenderness to palpation to the musculature of the calf.

Findings of the initial workup by the primary care provider were negative for deep vein thrombosis on Doppler ultrasonography and negative for arterial insufficiency on ankle-brachial pressure index. Electromyography findings were negative for myopathic or neuropathic abnormalities. Magnetic resonance imaging (MRI) scans of the lower extremity showed hyperintensity on fat-suppressed T1-weighted images of the musculature with associated subcutaneous nodularity (Figures 1 and 2).

Figures 1 and 2. MRI scans of the right lower extremity showed nodularities and nonspecific inflammation within the leg muscles, particularly the tibialis anterior and gastrocnemius muscles.

At that time, malignancy was a concern, so the patient was referred to an orthopedic oncologist, who performed a biopsy of the subcutaneous nodule. The biopsy showed nonspecific fibrotic changes, and the results were nondiagnostic. She was then referred to the rheumatology clinic for further evaluation.

The results of an autoimmune panel—including antinuclear antibodies, anti-Sjogren syndrome-related antibodies, rheumatoid factor, anticyclic citrullinated peptide, anti-Jo-1 antibodies, antineutrophil cytoplasmic antibodies, lupus anticoagulant, anti-β₂ glycoprotein antibodies, anticardiolipin antibodies, and cryoglobulin levels—were negative. Infectious serology test results—including hepatitis B viral serum antigen and core antibody, hepatitis C virus antibody, HIV 1/2 p24 antigen, Treponema pallidum antibodies, and interferon-γ release assay for tuberculosis—also were negative.

Results of other laboratory studies, including a complete blood cell count, a comprehensive metabolic panel, urinalysis, serum protein electrophoresis, and measurements of thyrotropin, creatinine kinase, aldolase, and lactate dehydrogenase, were all unremarkable. Chest radiography and transthoracic echocardiography findings were also unremarkable. The only significant serologic finding was an elevated erythrocyte sedimentation rate of 92 mm/h and an elevated C-reactive protein level of 10 mg/L.

After the initial workup and nondiagnostic initial biopsy of the subcutaneous nodule, we then felt it was important to obtain a biopsy specimen of the muscle tissue that appeared abnormal on the MRI, since the first biopsy had little muscle tissue and also had not been performed with a muscle biopsy protocol. The resulting muscle biopsy from the right gastrocnemius muscle revealed multifocal muscle-limited medium-vessel vasculitis (Figure 3).

Figure 3. Pathology slide from the right gastrocnemius muscle biopsy using hematoxylin-eosin staining showing a vessel with complete obliteration of its lumen (arrow). Increased endomysial capillaries/neovascularization is appreciated in the area surrounding the vessel. Notable inflammation and perimysial connective tissue are appreciated. (Image courtesy of Zarife Sahenk, MD, Department of Pathology, Children’s Hospital, Ohio State University, Columbus, Ohio.)

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