Surrogate Immunohistochemical Markers of Proliferation and Embryonic Stem Cells in Distinguishing Ameloblastoma from Ameloblastic Carcinoma.

PURPOSE: The current study aimed to investigate the use of surrogate immunohistochemical (IHC) markers of proliferation and stem cells to distinguish ameloblastoma (AB) from ameloblastic carcinoma (AC). METHODS: The study assessed a total of 29 ACs, 6 ABs that transformed into ACs, and a control cohort of 20 ABs. The demographics and clinicopathologic details of the included cases of AC were recorded. The Ki-67 proliferation index was scored through automated methods with the QuPath open-source software platform. For SOX2, OCT4 and Glypican-3 IHC, each case was scored using a proportion of positivity score combined with an intensity score to produce a total score. RESULTS: All cases of AC showed a relatively high median proliferation index of 41.7%, with statistically significant higher scores compared to ABs. ABs that transformed into ACs had similar median proliferation scores to the control cohort of ABs. Most cases of AC showed some degree of SOX2 expression, with 58.6% showing high expression. OCT4 expression was not seen in any case of AC. GPC-3 expression in ACs was limited, with high expression in 17.2% of ACs. Primary ACs showed higher median proliferation scores and degrees of SOX2 and GPC-3 expression than secondary cases. Regarding SOX2, OCT4 and GPC-3 IHC expression, no statistically significant differences existed between the cohort of ABs and ACs. CONCLUSION: Ki-67 IHC as a proliferation marker, particularly when assessed via automated methods, was helpful in distinguishing AC from AB cases. In contrast to other studies, surrogate IHC markers of embryonic stem cells, SOX2, OCT4 and GPC-3, were unreliable in distinguishing the two entities.

Correlative imaging and histopathology of a complicated sinonasal teratocarcinosarcoma.

Sinonasal teratocarcinosarcoma (SNTCS) is a highly malignant and rare tumour characterised by a complex admixture of teratomatous and carcinosarcomatous components. In the head and neck area, it almost exclusively occurs in the sinonasal cavities; however, rare instances of nasopharyngeal and oral cavity involvement have been reported, with fewer than 100 cases reported in the literature. Contribution: The contributed case involves the correlative CT, MRI and histopathology of a sinonasal teratocarcinosarcoma with intracranial involvement.

The Prevalence of Human Papillomavirus-Positive Oropharyngeal Squamous Cell Carcinoma at One of the Largest Tertiary Care Centers in Sub-Saharan Africa.

CONTEXT.­: Limited data exist on the prevalence of human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinoma in sub-Saharan Africa. OBJECTIVE.­: To determine the prevalence of HPV-positive oropharyngeal squamous cell carcinoma at a large tertiary care center in South Africa. DESIGN.­: A total of 266 oropharyngeal squamous cell carcinomas diagnosed during an 11-year period (2007-2017) were selected for evaluation. Cases staining positive for p16 immunohistochemistry were evaluated for high-risk HPV using the BD Onclarity assay (BD Diagnostics, Sparks, Maryland). RESULTS.­: Of 266 oropharyngeal squamous cell carcinomas, 14% (n = 36) were positive for p16. Polymerase chain reaction for high-risk HPV performed on the p16-positive cases was negative in 23 cases and positive in 13 cases (13 of 266; 5%). p16 showed a positive predictive value of 36.1%. The HPV subtypes were HPV-16 (n = 10), HPV-18 (n = 1), HPV-52 (n = 1), and HPV-31 (n = 1). Human papillomavirus-positive cases occurred in 10 men and 3 women (mean age, 51 years) and arose from the tonsil (n = 10) or base of the tongue (n = 3). The HPV-positive cases were non-keratinizing (n = 10) or partially keratinizing (n = 1). Partially/nonkeratinizing cases revealed a modest improvement in p16 positive predictive value (11 of 21; 52.4%). CONCLUSIONS.­: The presence of high-risk HPV in 5% of cases suggests that high-risk HPV is a minor etiologic agent in oropharyngeal squamous cell carcinoma in this region. Given its suboptimal positive predictive value, p16 is not a reliable marker for high-risk HPV infection in this region. When p16 is positive, HPV-specific testing is necessary. The identification of less common high-risk HPV types, HPV-52 and HPV-31, may influence current local vaccination strategies.

Metastatic amelanotic melanoma to the mandible mimicking benign odontogenic neoplasm.

Metastatic lesions to the jaws are rare and represent about 1% of all malignancies in the oral cavity. They are not usually considered as part of the differential diagnosis due to their paucity and unusual clinico-pathological features leading to diagnostic challenges. We report on a rare case of metastatic melanoma to the anterior mandible in a 58 year old Caucasian female that mimicked benign odontogenic tumour. The lesion posed a diagnostic challenge as it clinically and radiographically presented as a well-defined radiolucency with minimal bony destruction and no pigmentation or ulceration of the oral mucosa. Histological examination was also challenging as the lesion was not part of the differential diagnosis and a process of exclusion was employed to narrow the possible diagnoses. The tumour cells were immunoreactive with S100, HMB45 and SOX10 which raised the suspicion of melanoma. MELAN A confirmed the diagnosis of amelanotic melanoma. The patient underwent resection of the mandible with neck dissection and fibula free flap reconstruction. In conclusion, clinicians should always keep in mind that melanoma has diverse clinico-pathological presentations and hence is known as "the great mimicker". It should always be suspected in patients who present with unusual lesions in the jaws that do not conform to other more common odontogenic neoplasms.

Corrigendum: Not always 'squame': The rare entity of follicular dendritic cell sarcoma of the tonsil presenting with cervical nodal metastases.

[This corrects the article DOI: 10.4102/sajr.v24i1.1978.].

Not always 'squame': The rare entity of follicular dendritic cell sarcoma of the tonsil presenting with cervical nodal metastases.

Although squamous cell carcinoma accounts for the overwhelming majority of head and neck malignant neoplasms, extranodal follicular dendritic cell sarcoma (FDCS) of the pharyngeal region can have a similar clinical presentation. The histopathological features of this rare entity have been described and emphasised in the literature. We present the case of a 65-year-old male patient with FDCS of the tonsil to illustrate the radiologic findings of FDCS and also highlight this infrequent but salient differential diagnosis for adult head and neck neoplasia.

An Endotracheal Plasmablastic Lymphoma.

We describe an exceptionally rare case of a male patient with newly diagnosed advanced human immunodeficiency virus (HIV) infection, who presented with a plasmablastic lymphoma involving the right maxillary alveolar ridge with associated cervical lymphadenopathy. On a staging positron emission tomography computed tomography (PET-CT) scan, he was incidentally found to have an endotracheal tumour involving the anterolateral aspect of the mid-trachea. The tumour appeared to be well-vascularised at bronchoscopy and was confirmed as well-differentiated plasmablastic lymphoma. Plasmablastic lymphoma is a rare form of non-Hodgkin lymphoma and is associated with HIV. Tracheal involvement to the extent seen in our patient is exceptionally rare, and, to the best of our knowledge, has never been described.