COL1A1 and spindle cell neoplasm: Basically, the histologically and immunophenotypically (CD34 positive) overlapping pediatric lesions are often considered in the differential diagnoses, such as plaque-like CD34-positive dermal fibroma (lack of COL1A1-PDGFB), fibroblastic connective tissue nevus, fibrous hamartoma of infancy (EGFR exon 20 insertion/duplication mutations), pediatric NTRK-rearranged spindle cell neoplasm (co-expression of CD34 and S100, and NTRK-positive expression or rearrangement), lipofibromatosis, and plexiform myofibroblastoma.