555 - A Rare Case of Fibrolipomatous Hamartoma of Bilateral Tibial Nerve

Case Diagnosis: Fibrolipomatous Hamartoma of Bilateral Tibial Nerve

Case Description: 78 year old male with past medical history of left basal ganglia and right cerebellar ischemic strokes, lumbar stenosis with bilateral foot drop, peripheral neuropathy, and diabetes mellitus presented to outpatient clinic for evaluation of abnormality in gait. Patient with history of frequent falls and paresthesia of bilateral feet and ankles. Physical exam significant for dorsiflexion 2/5 and plantarflexion 3/5 bilaterally and gross neurologic sensation diminished bilaterally distal to shin. MRI Imaging of bilateral lower extremities showed bilateral fibrolipomatous hamartoma of tibial nerve. Patient referred to prosthetics for ankle foot orthosis, and to physical therapy for evaluation of Walkasins device.

Discussions: Fibrolipomatous hamartomas (FLH) are defined as benign, sporadic, and slowly progressive lesions caused by proliferation of fibroadipose tissue within the perineurium and endoneurium of peripheral nerves. FLH commonly affects upper extremity, specifically the median nerve. Literature review shows it is rare to occur in the lower extremity and even more rare to occur in bilateral lower extremities. Aside from physical exam, advanced imaging techniques such as MRI are necessary in making the diagnosis. We present a uniquely rare case of a FLH in bilateral lower extremities of the tibial nerve.

Conclusions: Presentation of gait abnormality and frequent falls is a common presentation of patients presenting to outpatient clinic. Case highlights multifactorial etiology of motor and sensory deficits. Patient presented with history of previous strokes, peripheral neuropathy, and lumbar stenosis which could explain symptomatology, however, this case demonstrated the importance of imaging and exam in assisting to make the diagnosis of fibrolipomatous hamartomas of bilateral tibial nerves.