Chronic Calf Pain Caused by Fibroma-Induced Chronic Inflammation Around the Tibial and Peroneal Nerves that Was Misdiagnosed as Centralized Neuropathic Pain: A Case Report.

INTRODUCTION: The etiology of calf pain varies widely; therefore, it is difficult to diagnose and requires careful history taking and physical examination by primary care unit physicians. Because ultrasonography is easy to perform, cheap, and readily available to physicians during a routine consultation, it is the first choice of modality for the evaluation of calf pain. However, simple inflammation around the nerve should also be considered as a possible etiology. Here we describe a 35-year-old man with chronic pain in the right calf that was actually caused by fibroma-induced chronic inflammation around the tibial and peroneal nerves but misdiagnosed as centralized neuropathic pain.

CASE REPORT: The patient presented with chronic pain and a tingling sensation in the right calf. He had a slowly growing tibial nerve neurilemmoma that was excised at 28 years of age; however, the pain and tingling sensation persisted. He visited several hospitals for 7 years and was misdiagnosed with peripheral nerve injury-induced neuropathic pain. At 35 years of age, he visited our hospital for further evaluation. Ultrasonography revealed a mass in the popliteal region, which was excised and confirmed to be a fibroma via histopathological analysis. Severe inflammation was observed in the operative field. His symptoms finally ameliorated after this surgery.

CONCLUSION: The findings from this case suggest that ultrasonography should be used as the primary modality for the evaluation of calf pain. Although the features of unresolved calf pain are similar to those of neuropathic pain, more curable etiologies should be considered.