Lipofibromatosis-like neural tumor
Lipofibromatosis-like neural tumor (LPF-NT) is an extremely rare soft tissue tumor first described by Agaram et al in 2016. As of mid-2021, at least 39 cases of LPF-NT have been reported in the literature. LPF-NT tumors have several features that resemble lipofibromatosis (LPF) tumors, malignant peripheral nerve sheath tumors, spindle cell sarcomas, low-grade neural tumors, peripheral nerve sheath tumors, and other less clearly defined tumors; Prior to the Agaram at al report, LPF-NTs were likely diagnosed as variants or atypical forms of these tumors. The analyses of Agaram at al and subsequent studies uncovered critical differences between LPF-NT and the other tumor forms which suggest that it is a distinct tumor entity differing not only from lipofibromatosis but also the other tumor forms. LPF-NTs are locally invasive, are commonly treated by surgical excision, and have a relatively high rate of local recurrence if their surgical excisions are incomplete. They are generally considered to be benign, non-metastasizing (i.e. not spreading to other parts of the body) tumors. However, one case of LFT-NT reported by Agaram et al was associated with metastasis, apparently as a result of the tumor's cells transformation into a malignant sarcoma. Further studies are needed to determine the frequency of such cases and the overall metastatic potential of LPF-NT. LPF-NTs were given the "neural tumor" terminology because in at least some cases: 1) their tumor cells express S100 and CD34 but not SOX10 proteins, a pattern that is often found in neural and neuroectodermal tumor cells; and 2) their histopathology consists of tumor cell infiltrations into adipose tissues in a pattern that is very similar to that found in some low grade malignant peripheral nerve sheath tumors. Presentation Lipofibromatosis-like neural tumors have been reported in the English literature to develop in children and young adults aged from 2 to 38 years (median age ~17 years). However, a recent study in the Chinese literature reported on three cases in infants <1 year old. LPF-NTs have almost always been superficially situated and occurring primarily in the legs and arms with fewer cases in the head, neck, and trunk areas. Three cases of primary and one case of recurrent LPF-NT tumors presented with infiltration into the adjacent skeletal muscles and one recently reported case presented with the tumor situated in, and limited to, the lumbar spine. The tumors have ranged from 1.3 cm to 8.7 cm in maximum diameter; may be tender but usually are painless (although the lumbar spine tumor presented with intermittent abdominal pain); and may be pigmented. In as high as 30% of cases, patients treated with surgical removal of the LPF-NT have presented with recurrent tumors at the site of surgery. The recurrent tumors have, in general, showed similar features to the primary tumors. In particular, they almost always continue to act in a non-malignant manner. Pathology Histpathologically, hemotoxin and eosin dye-stained and otherwise properly prepared LPF-NT tissues consist of mildly to moderately atypical spindle-shaped cells that variably infiltrate into subcutaneous adipose (i.e. fat) tissues. The spindle-shaped