Biomarker NTRK Coverage from Every Angle

Lipofibromatosis-Like Neural Tumor: Case Featuring an NTRK Abnormality

By: Lauren Harrison, MS
Posted: Thursday, December 9, 2021

A case report published in the Saudi Journal of Medicine & Medical Sciences described an unusual presentation of lipofibromatosis-like neural tumor in a 50-year-old man with a right foot mass. This type of neural tumor more commonly presents in the distal extremities of children and young adults. Joseph White, DO,  of the Medical College of Georgia, and his colleagues detailed how next-generation sequencing revealed a mutation that aided in the diagnosis: an LMNA-NTRK1 fusion.

“The authors recommend including lipofibromatosis-like neural tumor in the differential diagnosis of masses or lesions that are fibrofatty tumors. A biopsy is helpful to follow the case accordingly, and surgical excision remains the choice of treatment,” concluded the writers.

A 50-year-old man had a poorly defined 3.9 x 2.4 x 2.3 cm soft-tissue mass on the medial aspect of the first metatarsal. There was no skin discoloration, and the foot was neurovascularly intact. An ultrasound-guided biopsy was taken of the mass, which revealed a spindle neoplasm with fascicular proliferation of fibroblastic to somewhat neural-appearing cells growing throughout the connective tissue. The cells stained positive for S-100, CD34, epithelial membrane antigen, and PAN-TRK. The tumor was negative for desmin, smooth muscle, and pan-keratin. Next-generation sequencing was performed on the sample, revealing an LMNA-NTRK1 fusion. This fusion, combined with the immunohistochemical findings, were consistent with a diagnosis of LPF-NT. The patient underwent surgical resection and had no pain or evidence of tumor recurrence three months later.

LPF-NT tumors characteristically show co-expression of S-10, CD34, and PAN-TRK. They typically contain NTRK1 gene rearrangements, including TPR-NTRK1, TPM3-NTRK1 and most commonly, lipofibromatosis-like neural tumor. The presence of S-100 staining and detection of NTRK1 gene abnormalities may distinguish lipofibromatosis from lipofibromatosis-like neural tumor tumors.

Disclosure: The authors reported no conflicts of interest.

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