Denervation of muscle usually leads to muscle atrophy with fatty replacement but, uncommonly, also results in muscle hypertrophy or pseudohypertrophy with fatty replacement. We report the ultrasonographic and magnetic resonance imaging (MRI) findings of a patient with diffuse fatty infiltration of calf muscles as a result of denervation pseudohypertrophy. The elevated fasting glucose, neurogenic electromyographic changes, and muscle atrophy with adipose tissue infiltration are consistent with diabetic neuropathy as the cause of denervation pseudohypertrophy. Lumbosacral radiculopathy and plexopathy were excluded by MRI. The imaging features reported in the literature are reviewed. The important differential diagnosis of infiltrating lipoma and denervation hypertrophy, as well as other causes of monomelic hypertrophy or swelling, is discussed. This case report demonstrates the importance of MRI, with clinical, biochemical, electrophysiological, and histologic correlation in the diagnosis of denervation pseudohypertrophy. Correct diagnosis of denervation pseudohypertrophy has an important role in guiding further investigations and treatment of the disease and the underlying cause.

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Granular cell tumor (GCT), despite its putative neural origin, commonly occurs in extraneural sites; only six single case reports of intraneural GCT have been described.We report an unique case as the only one with motor dysfunction, the longest duration of symptoms, and largest tumor size with resultant muscle atrophy and fatty infiltration. Upon review of these cases, the striking feature of intraneural GCT lies in its histologic variety, ranging from benign GCT, through plexiform, hybrid GCT and perineurioma to malignant GCT, encompassing the full spectrum of extraneural GCT.As the immunophenotypes of schwannoma and GCT are not exactly identical, together with evidence from ultrastructural studies, the more reasonable and likely possibility is that GCT originates from undifferentiated mesenchymal cells acquiring partial schwannian differentiation. Such postulation by virtue of the widespread occurrence of mesenchymal cells in the soft tissue, better explains the topographic distribution of GCT in extraneural and intraneural location. K E Y W O R D S granular cell tumor, histogenesis, histologic spectrum, intraneural, nerve