Melanoma of the oral cavity is a rare malignancy that carries a poor prognosis. We identified 46 new cases of both primary and metastatic melanoma to the oral cavity. Following IRB approval, these cases were obtained from the Oral Pathology Biopsy Service archives of the UF College of Dentistry (1994Dentistry ( -2014, the UK College of Dentistry (1997Dentistry ( -2015, and the UM Medical Center . All slides were reviewed. The location, age, race, gender, clinical impression, duration of lesion, histopathologic diagnosis, and histopathologic features were recorded. Cases from the facial skin and those with an ambiguous diagnosis were excluded. Forty-six cases fulfilled the inclusion criteria with 32 primary cases, 11 known metastases, and 3 cases where metastasis could not be excluded. The primary cases included a total of 20 females and 12 males with an average age of 66.7 (range 27-95), and the majority (80 %) of the patients were Caucasian when race was known. Twenty-two of the 32 primary cases (68.8 %) were located in the maxillary mucosa, 5 in the mandibular mucosa or bone, and 5 in other locations. The clinicians' impressions varied from benign fibrous growths to high grade malignancies. The histopathology varied widely among the cases, however two cell types predominated (often in combination): epithelioid cells (50.0 %) and spindle cells (50.0 %). Only 53.1 % demonstrated melanin pigmentation. Oral melanoma remains one of the most diverse clinical and histopathologic diagnoses. Better understanding of this neoplasm may promote earlier diagnosis and may lead to improved outcomes.

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Oral epithelial dysplasia (OED) is a precursor state usually preceding oral squamous cell carcinoma (OSCC). Histological grading is the current gold standard for OED prognostication but is subjective and variable with unreliable outcome prediction. We explore if individual OED histological features can be used to develop and evaluate prognostic models for malignant transformation and recurrence prediction. Digitised tissue slides for a cohort of 109 OED cases were reviewed by three expert pathologists, where the prevalence and agreement of architectural and cytological histological features was assessed and association with clinical outcomes analysed using Cox proportional hazards regression and Kaplan–Meier curves. Within the cohort, the most prevalent features were basal cell hyperplasia (72%) and irregular surface keratin (60%), and least common were verrucous surface (26%), loss of epithelial cohesion (30%), lymphocytic band and dyskeratosis (34%). Several features were significant for transformation (p < 0.036) and recurrence (p < 0.015) including bulbous rete pegs, hyperchromatism, loss of epithelial cohesion, loss of stratification, suprabasal mitoses and nuclear pleomorphism. This led us to propose two prognostic scoring systems including a ‘6-point model’ using the six features showing a greater statistical association with transformation and recurrence (bulbous rete pegs, hyperchromatism, loss of epithelial cohesion, loss of stratification, suprabasal mitoses, nuclear pleomorphism) and a ‘two-point model’ using the two features with highest inter-pathologist agreement (loss of epithelial cohesion and bulbous rete pegs). Both the ‘six point’ and ‘two point’ models showed good predictive ability (AUROC ≥ 0.774 for transformation and 0.726 for recurrence) with further improvement when age, gender and histological grade were added. These results demonstrate a correlation between individual OED histological features and prognosis for the first time. The proposed models have the potential to simplify OED grading and aid patient management. Validation on larger multicentre cohorts with prospective analysis is needed to establish their usefulness in clinical practice.

Spindle cell/sclerosing rhabdomyosarcoma (S-ScRMS) was recently recognized in 2013 by the World Health Organization (WHO) as a stand-alone entity (Parham et al., WHO classification of tumours of soft tissue and bone, IARC Press, Lyon, 2013). Historically, the spindle cell and sclerosing variants were subcategorized under embryonal type rhabdomyosarcoma. Current data supports that certain S-ScRMS cases have a more aggressive clinical course with reduction of long-term survival, and those found in the head and neck region often exhibit extensive local recurrence. Furthermore, due to variable histopathologic appearances and immunohistochemical findings, misdiagnosis is common. We aim to report the variability in histopathologic patterns, immunohistochemical findings, radiographic features, and clinical data on three new cases of S-ScRMS presenting in the oral cavity of young adult males (ages 22, 24, and 39 years). The English-language literature on S-ScRMS is briefly reviewed as well.