pyrimidinones and Salivary-Gland-Neoplasms

Malignant melanoma is a well-known diagnostic pitfall, given its propensity to metastasize to different sites and mimic various entities. In this report, we present a fine-needle aspiration biopsy (FNA) of a metastatic melanoma with basaloid features that is occurring in the preauricular/parotid area. The patient is a 17-year-old male with a history of excision of melanoma of the left temple, and was undergoing adjuvant treatment with nivolumab. The prior excision was positive for S100, HMB-45, melan-A, and tyrosinase. On follow-up, he presented with non-FDG avid left preauricular area lesions. FNA was performed, and on-site evaluation demonstrated a cellular basaloid neoplasm with focal fibrillary stroma. Immunohistochemical stains revealed that the tumor cells were positive for SOX-10, S100, MITF, and HMGA2, and were negative for HMB-45, melan-A, tyrosinase, p63, cam 5.2 and PLAG1. The positive S100, SOX-10, and MITF results and negative cam 5.2 result supported the diagnosis of melanoma. Nivolumab was then stopped, Dabrafenib/Trametinib were started, and the patient underwent excision of the nodules. Nine-months later, he developed a rib metastasis that was positive for S100, SOX-10, melan-A, and tyrosinase. This report emphasizes that melanoma involving the parotid gland region has the potential to be misdiagnosed by FNA as a salivary gland neoplasm because of overlapping cytologic features and immunophenotypes. This pitfall is avoided by careful morphologic analysis and judicious use of ancillary studies.

Topics: Adolescent; Antineoplastic Agents; Biomarkers, Tumor; Biopsy, Fine-Needle; Diagnosis, Differential; Humans; Imidazoles; Male; Melanoma; Neoplasm Metastasis; Nivolumab; Oximes; Pyridones; Pyrimidinones; Salivary Gland Neoplasms

We show that activation of Wnt/β-catenin and attenuation of Bmp signals, by combined gain- and loss-of-function mutations of β-catenin and Bmpr1a, respectively, results in rapidly growing, aggressive squamous cell carcinomas (SCC) in the salivary glands of mice. Tumours contain transplantable and hyperproliferative tumour propagating cells, which can be enriched by fluorescence activated cell sorting (FACS). Single mutations stimulate stem cells, but tumours are not formed. We show that β-catenin, CBP and Mll promote self-renewal and H3K4 tri-methylation in tumour propagating cells. Blocking β-catenin-CBP interaction with the small molecule ICG-001 and small-interfering RNAs against β-catenin, CBP or Mll abrogate hyperproliferation and H3K4 tri-methylation, and induce differentiation of cultured tumour propagating cells into acini-like structures. ICG-001 decreases H3K4me3 at promoters of stem cell-associated genes in vitro and reduces tumour growth in vivo. Remarkably, high Wnt/β-catenin and low Bmp signalling also characterize human salivary gland SCC and head and neck SCC in general. Our work defines mechanisms by which β-catenin signals remodel chromatin and control induction and maintenance of tumour propagating cells. Further, it supports new strategies for the therapy of solid tumours.

Topics: Animals; beta Catenin; Bone Morphogenetic Proteins; Bridged Bicyclo Compounds, Heterocyclic; Carcinoma, Squamous Cell; Cell Proliferation; CREB-Binding Protein; Epigenesis, Genetic; Head and Neck Neoplasms; Histone Methyltransferases; Histone-Lysine N-Methyltransferase; Humans; Mice; Mice, Inbred NOD; Mice, Mutant Strains; Mice, SCID; Mice, Transgenic; Mutation; Myeloid-Lymphoid Leukemia Protein; Neoplastic Stem Cells; Pyrimidinones; Salivary Gland Neoplasms; Transplantation, Heterologous; Wnt Signaling Pathway