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Alexander Drilon, MD

Gregory J. Riely, MD, PhD


Case Report: NTRK-1–Associated Lipofibromatosis-Like Neural Tumor

By: Emily Rhode
Posted: Tuesday, December 6, 2022

A case report published in the Journal of Cutaneous Pathology presented a previously undescribed feature of a lipofibromatosis-like neural tumor in an 11-year-old boy with a lesion on his back. Simon Warren, MBBS, of Indiana University, Indianapolis, and colleagues detailed how next-generation sequencing an NTRK-1–associated soft-tissue tumor with nodules and peripheral accentuation of cellularity, such as those found in epithelioid malignant peripheral nerve sheath tumors (MPNST).

“The tumor type of this group of neoplasms is speculated to be neural. Our mRNA expression data support neural differentiation, and the presence of MPNST-like nodules with peripheral accentuation of cellularity in this case is also in keeping with neural differentiation,” concluded the authors.

An 11-year-old boy had a 14-cm lesion showing irregularity, induration, and pigmentation on his back. The lesion had been present since the patient was 1 week old and had been recently growing. Following an excisional biopsy, the lesion was removed, with clear margins. The biopsy revealed a spindle cell neoplasm with multiple large cellular nodules and peripheral accentuation of cellularity throughout the dermis and subcutis.

The cells stained positive for CD34, S-100, CD30, and PAN-NTRK. The lesion tested negative for Sox-10. Next-generation sequencing further revealed an LMNA::NTRK1 fusion. This fusion, combined with the histopathologic and immunohistochemical findings, was consistent with a diagnosis of lipofibromatosis-like neural tumor. The 9-month follow-up showed the patient remained disease-free.

Although the tumor in this case expressed a similar histopathology to lipofibromatosis, its reactivity for S100 and the presence of an NTRK-1 kinase fusion suggest it closely resembles the more cellular variant of NTRK-1 kinase fusion tumors. However, the authors noted, the distinctive nodules with peripheral accentuation of cellularity support the neural differentiation of lipofibromatosis described in previous studies.

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