Histopathologic and genetic findings in atypical spindle cell/pleomorphic lipomatous tumors and atypical pleomorphic fibromas.

BACKGROUND: Spindle cell lipomas, pleomorphic lipomas (SCL/PLs), and pleomorphic fibromas (PF) are tumors with loss of retinoblastoma (RB). The latest World Health Organization classification includes a category of atypical spindle cell/pleomorphic lipomatous tumors (ASPLT), which encompasses tumors in this spectrum that show atypical histopathologic features. We have observed PFs that show similar atypical features. METHODS: Cases of SCL/PL and PF with atypical features were collected from tissue archives between 2010 and 2019. Genetic alterations were investigated using array comparative genomic hybridization (aCGH). RESULT: Of 15 cases found, most tumors were dermal based with fibrocytic or fibroadipocytic appearance and occasional lipoblasts. All cases had a high proliferation index with atypical mitotic figures in 71% of cases. Chromosome 13q loss was present in all cases with CGH data. Additional recurrent chromosomal losses included 17p, 16q, 17q, 20p, 4, and 10. No recurrence was found in limited follow-up. CONCLUSIONS: ASPLTs are characterized by loss of RB, prominent nuclear pleomorphism, mitotic activity including atypical mitotic figures, and genomic instability with multiple chromosomal aberrations. A similar group of tumors with these histopathologic features lacks lipomatous differentiation, and we propose the diagnosis of atypical PF as a fibromatous variant of ASPLT. Limited clinical follow-up appears benign.

Metal allergy hypersensitivity after posterior thoracic spinal fusion: A case report and review of the literature.

Background: Spine surgeons rarely consider metal allergies when placing hardware, as implants are thought to be inert. Case Description: A 32-year-old male presented with a skin rash attributed to the trace metal in his spinal fusion instrumentation. Patch testing revealed sensitivities to cobalt, manganese, and chromium. He underwent hardware removal and replacement with constructs of commercially pure titanium. His skin findings resolved at 2 weeks after surgery and were stable at 6 weeks. Conclusion: Hypersensitivity to metal (i.e., metal allergy) should be considered before performing instrumented spinal fusions.