Lipofibromatosis

Lipofibromatosis (LPF) is an extremely rare soft tissue tumor which was first clearly described in 2000 by Fetsch et al as a strictly pediatric, locally invasive, and often recurrent (at the site of its surgical removal) tumor. It is nonetheless a non-metastasizing, i.e. benign, tumor.^[1] While even the more recent literature has sometimes regarded LPF as a strictly childhood disorder,^[2][3] rare cases of LPF have been diagnosed in adults.^[4][5] The diagnosis of lipofibromatosis should not be automatically discarded because of an individual's age.^[4][5]

Based primarily on histopathologic (i.e. microscopic appearance of specially prepared tissue) analyses, lipofibromatosis was initially regarded as either a type of, or very similar to, aponeurotic fibroma (also termed calcifying aponeurotic fibroma),^[6] fibrous hamartoma of infancy,^[7] EWSRI-SMAD3-rearranged fibroblastic tumor (also termed EWSR1-SMAD3-positive fibroblastic tumor),^[8] or infantile digital fibromatosis.^[7] However, further analyses of these tumors' various differences, particularly in the gene abnormalities that their neoplastic cells express, led the World Health Organization in 2020 to classify LPF and each of the four other tumors as distinctly different forms in the category of fibroblastic and myofibroblastic tumors.^[9]

Lipofibromatosis-like neural tumor was defined in 2016 as a disorder which initial studies regarded to be a variant of lipofibromatosis.^[10][11] However, more recent studies have emphasized critical differences in the clinical presentations and gene abnormalities between these two tumors.^[12] Here, lipofibromatosis-like neural tumor is considered to be a distinct tumor form with its own article.