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The article discusses a rare case of an ectomesenchymal chondromyxoid tumor involving the hard palate, a location uncommon for this type of tumor. The patient, a 49-year-old man, presented with a painless mass on the hard palate, which was surgically removed and confirmed to have the characteristic RREB1::MRTFB gene fusion. Molecular testing using next-generation RNA sequencing was crucial in confirming the diagnosis and ruling out other similar neoplasms. The article emphasizes the importance of accurate diagnosis through a combination of histomorphology, immunophenotypical profile, and molecular genetic analysis. [Extracted from the article]

More than 3.5 million nonmelanoma skin cancers were treated in 2006; of these 700,000 were cutaneous squamous cell carcinomas (cSCCs). Despite clear environmental causes for cSCC, studies also suggest genetic risk factors. A cSCC susceptibility locus, Skts5, was identified on mouse chromosome 12 by linkage analysis. The orthologous locus to Skts5 in humans maps to 7p21 and 7q31. These loci show copy number increases in ∼10% of cSCC tumors. Here, we show that an additional 15-22% of tumors exhibit copy-neutral loss of heterozygosity. Furthermore, our previous data identified microsatellite markers on 7p21 and 7q31 that demonstrate preferential allelic imbalance (PAI) in cSCC tumors. On the basis of these results, we hypothesized that the human orthologous locus to Skts5 would house a gene important in human cSCC development and that tumors would demonstrate allele-specific somatic alterations. To test this hypothesis, we performed quantitative genotyping of 108 single nucleotide polymorphisms (SNPs) mapping to candidate genes at human SKTS5 in paired normal and tumor DNAs. Nine SNPs in HDAC9 (rs801540, rs1178108, rs1178112, rs1726610, rs10243618, rs11764116, rs1178355, rs10269422 and rs12540872) showed PAI in tumors. These data suggest that HDAC9 variants may be selected for during cSCC tumorigenesis.

Solitary circumscribed neuroma formerly known as palisaded encapsulated neuroma is a rare, benign neural tumor that usually presents as a painless firm nodule or papule on the face and within oral cavity, although they can occur elsewhere on the body. No association with neurofibromatosis has been reported in the literature. Herein, we report, a previously unreported unique association of neurofibromatosis type 2 (NF-2) with multiple cutaneous solitary circumscribed neuromas in a 24-year-old female. A 24-year-old female with history of NF-2 presented with two slow-growing soft-to-firm papules on the chin and forehead that had been gradually increasing in size over a period of 5 years. The papule on the chin was increasingly tender to palpation. Histologic sections demonstrated a dermal based almost encapsulated, smoothly contoured tumefactive mass composed of spindle cell proliferation with neuroid structures and foci of palisaded growth (resembling schwannoma) and intralesional cleft like spaces. By immunohistochemistry, the lesional cells were strongly and diffusely positive for S-100 and SOX10 with multifocal neurofilament expression while the "capsule" was diffusely reactive for epithelial membrane antigen. The overall features were considered prototypic for solitary circumscribed neuroma. The patient is 18-months post-surgical resection with no evidence of recurrence. In summary, we report for the first time a case of multiple solitary circumscribed neuromas in a patient with known NF2. We highlight pertinent diagnostic clues relevant to surgical pathologist to facilitate recognition (as this tumor is often mistaken for schwannoma or neurofibroma). The clinical behavior is excellent and surgical resection is considered curative. [ABSTRACT FROM AUTHOR]