Lipofibromatosis-like neural tumour: a clinicopathological study of ten additional cases of an emerging novel entity.

We present our experience with ten cases of lipofibromatosis-like tumour (LPF-NT) to further characterise this newly described neoplasm. There were six males and four females with a mean age of 12.8 years (range 2-37 years). Tumours occurred in the neck (n = 3), buttock (n = 2), chest wall, flank, hip, hand and foot (n = 1). Histologically, they were composed of cellular fascicles of mildly to moderately atypical spindle cells displaying an infiltrative pattern reminiscent of lipofibromatosis or dermatofibrosarcoma protuberans. Immunohistochemically, all cases co-expressed S100 protein and CD34. FISH analysis revealed NTRK1 gene rearrangement in four of five cases tested. Clinical follow-up showed local recurrence in three cases but no evidence of metastasis. This study further supports that LPF-NT represents a novel entity of NTRK1-associated neoplasms. Awareness of its clinicopathological features, immunophenotypes and cytogenetic abnormalities helps pathologists arrive at the correct diagnosis.