Interactive Quiz: Calf Pain With Muscle-Limited Involvement

Welcome to Rheumatology Consultant’s latest interactive diagnostic quiz. Over the next few pages, we’ll present a case and ask you to make the diagnosis and treat the patient. Along the way, we’ll provide details about the case, and at the end, we’ll share the patient’s outcome.

Ready to get started? >>

First, let’s meet the patient …

A 37-year-old woman with no significant medical history had 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.

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 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.

Are you correct? >>

Answer: Magnetic resonance imaging

While the clinicians considered either computed tomography angiography of the abdomen or arteriography of the mesenteric or renal system, the lack of symptoms such as fever, weight loss, abdominal pain or angina, hypertension, renal insufficiency, hematuria, or proteinuria, made them feel as though there was no indication to do so.

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).

A biopsy of the subcutaneous nodule showed nonspecific fibrotic changes, and the results were nondiagnostic.

The results of an autoimmune panel, as well as of an infectious serology test, were negative. Chest radiography and transthoracic echocardiography findings, as well as results of other laboratory studies, were 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.

Are you correct? >>

Answer: Obtain a biopsy specimen of the muscle tissue that appeared abnormal on the MRI

After the initial workup and nondiagnostic initial biopsy of the subcutaneous nodule, the clinicians 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.

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Answer: Vasculitis

The resulting muscle biopsy from the right gastrocnemius muscle revealed multifocal muscle-limited medium-vessel vasculitis.

This patient’s case was unique in that her only symptom was lower extremity pain and swelling, without systemic organ system involvement. Vasculitis localized to a specific muscle without other systemic manifestations is rare, and very few cases have been reported in the literature.

After a muscle biopsy revealed vasculitis, she was promptly placed on prednisone, 60 mg, for 1 month, which led to a prompt resolution of her symptoms. She was then tapered to 5 mg by month 6.

Are you correct? >>

Answer: 6 months

After being tapered to prednisone, 5 mg, by month 6, the patient continued at this dose for the next 6 months.

At nearly 1 year after initiation of treatment, our patient’s vasculitis relapsed, and she again developed calf pain; the corticosteroid-sparing agent methotrexate was added to her regimen.

To read the full case report, see:

Ferdous A, Van Dyke K. Vasculitis presenting as calf pain with muscle-limited involvement [published online March 25, 2019]. Rheumatology Consultant. https://www.consultant360.com/article/rheumatology/vasculitis-presenting-calf-pain-muscle-limited-involvement.