Tyrosine kinase-altered spindle cell neoplasms with EGFR internal tandem duplications

In this study, we present two extra-renal pediatric spindle cell neoplasms with epidermal growth factor receptor (EGFR) internal tandem duplications (ITD). Histologically, these tumors demonstrated the same histologic features seen in other tyrosine kinase-altered spindle cell neoplasms, with one case showing abundant adipose tissue with cellular fibrous septae resembling lipofibromatosis and the other case showing fascicles of spindled cells resembling infantile fibrosarcoma. There was variable expression of CD34, S100, and SMA, and all cases were negative for panTRK. This case series adds to our molecular understanding of the spectrum of tyrosine kinase-altered spindle cell neoplasms and represents the first reported examples of EGFR ITDs in extra-renal tumors. The presence of EGFR alterations in the absence of gene fusions represents a potential therapeutic target and necessitates a broader testing panel for this group of tumors.

Automated summary

In this study, two cases of extra-renal pediatric spindle cell neoplasms with EGFR internal tandem duplications are reported. This is the first reported example of EGFR ITDs in extra-renal tumors. Broad testing for this group of tumors is necessary to identify potential therapeutic targets.