An intraneural location for benign granular cell tumours, as well as plexiform architecture with perineural localisation of granular cell tumours of the skin, has been described. We describe the first case of a plexiform intraneural granular cell tumour, morphologically akin to a plexiform neurofibroma. It presented in a 23-year-old woman who had multiple soft-tissue digital lesions on her right hand and one lesion on her left hand. The lesions presented with sensory neurological changes on physical examination. A plexiform architecture with an elongated mass with lobular growth, entirely encased within a fibrovascular connective tissue epineurial/perineurial coat, was noted. The histological findings of a monotonous polygonal and spindle cell proliferation with banal nuclear morphology and granular eosinophilic cytoplasm was typical of a granular cell tumour. The tumour was positive for the usual markers including periodic acid Schiff (PAS), S100 and CD68, and the intraneural location was demonstrated with recognition of the residual nerve bundles and myelinated axons on Luxol fast blue (LFB) staining. There was no history of neurofibromatosis type 1 or 2 in this patient. Recognition of this entity is important, as the natural history of this plexiform lesion is unknown, and the presence of multiple additional nodules in this patient requires further clinical follow-up.

Granular cell tumours are benign neoplasms of presumed peripheral nerve, Schwann cell origin. They have been described in numerous locations including the skin and soft tissue, breast, tongue, oesophagus and many other sites.^1–4 They have also been reported to be multiple in many cases^1,3,5,6 and associated with other malignant neoplasms.⁷ Plexiform granular cell tumours have been described in the skin, which are characterised by a lobular growth pattern with perineural involvement, …