This case series describes the clinical, imaging, and histological features of 27 lesions diagnosed as a benign fibrous mass not previously described in veterinary literature. The authors propose the name gingival mucoperiosteal fibroma (GMPF) to describe these fibrous lesions found in dogs. Histologically, GMPF is characterized by a lack of odontogenic tissue and various degrees of ossification. GMPFs affect adult dogs with an average age of 95 months (range 24-156 months) and appear as expansile growths with superficial appearance matching the surrounding gingiva. The mandibular incisive region is the most commonly affected region (n = 13) and most cases have some level of bone proliferation radiographically (n = 14). Histological examination of the masses shows poorly cellular fibrous tissue with thick interwoven collagen fibers. Bony invasion by the mass was not noted, though histological proliferation of bone was seen in 17 lesions. Surgical resection was curative in all cases when performed, and no recurrence was seen at time of follow-up. Fibrous lesions of the oral cavity in dogs are poorly defined and categorized, though numerous lesions have been described in both human and veterinary literature.

Four camels (Camelus dromedarius) presented to the Veterinary Teaching Hospital at King Faisal University with maxillary masses. On radiographs, the masses were multicystic and expanded the maxillary bone. The tumors were diagnosed by histopathologic examination as conventional ameloblastoma, two cases as intraosseous squamous cell carcinoma, and central odontogenic fibroma with ossification. To the authors\' knowledge, this is the first report of ameloblastoma in a camel, the first detailed description of maxillary squamous cell carcinoma in camels, and the first report of central odontogenic fibroma in any animal species.

BACKGROUND: The World Health Organization\'s (WHO) chapter on odontogenic and maxillofacial bone tumors provides a global reference for diagnosis of these tumors. In the fifth edition, the inclusion of consensus definitions and development of essential and desirable diagnostic criteria help improve recognition of distinct entities. These are key enhancements since the diagnosis of odontogenic tumors is largely based on histomorphology which is taken in combination with clinical and radiographic appearances.
METHODS: Review.
RESULTS: Despite delineation of diagnostic criteria for ameloblastoma, adenoid ameloblastoma, and dentinogenic ghost cell tumor, a subset of these tumors continues to show overlapping histological features that can potentially lead to misdiagnosis. Accurate classification may be challenging on small biopsies, but potentially enhanced by refining existing diagnostic criteria and utilization of immunohistochemistry and/or molecular techniques in a specific cases. It has become clear that the clinical and histologic features of the non-calcifying Langerhans cell-rich subtype of calcifying epithelial odontogenic tumor and the amyloid-rich variant of odontogenic fibroma converge into a single tumor description. In addition, this tumor shows remarkable clinical, histological overlap with a subset of sclerosing odontogenic carcinoma located in the maxilla. Benign perineural involvement vs perineural invasion is an underexplored concept in odontogenic neoplasia and warrants clarification to reduce diagnostic confusion with sclerosing odontogenic carcinoma.
CONCLUSIONS: While controversial issues surrounding classification and discrete tumor entities are addressed in the WHO chapter, ambiguities inevitably remain. This review will examine several groups of odontogenic tumors to highlight persistent knowledge gaps, unmet needs and unresolved controversies.

BACKGROUND: Granular Cell Odontogenic Fibroma (GCOF) is a rare odontogenic neoplasm reported over time with different names. The purpose of this study is to review all available data on the GCOF in the scientific literature, with a summary of all reported cases and a report of a new case.
METHODS: This review was conducted following the PRISMA guidelines. An electronic search was performed up to November 2022.
RESULTS: Thirty-nine studies reporting fifty-three cases were included. GCOF is a rare neoplasm among the odontogenic tumors, with a higher prevalence in women of the middle-aged and white population. This lesion occurs mostly on the posterior region of the mandible. Furthermore, based on clinical, radiographic, and histopathologic features, conservative treatment was the most reported choice with recurrence reported in two cases.
CONCLUSIONS: GCOF remains controversial due to the still unsolved histogenesis.

Tuberous sclerosis complex (TSC) is an autosomal dominant inherited disease characterized by systemic hamartoma and diverse systemic features. TSC1 and TSC2 are the causative genes, and mental retardation, epileptic seizures, and facial angiofibroma develop in many patients with the disease. The case of a patient with TSC who developed a central odontogenic fibroma of the mandible is reported here. The patient was a 21-year-old woman who was referred with a swelling of the labial gingiva in the region of the right lower lateral incisor and canine. Dental radiography revealed a multilocular radiolucent region with a clear boundary. The right lower lateral incisor and canine were continuous with the lesion and thus were excised en bloc. The lesion was encapsulated and easily dissected. The diagnosis on immunohistological staining was odontogenic fibroma without an epithelial component. TSC1/2 gene mutation causes abnormal activation of mammalian target of rapamycin (mTOR) downstream of the PI3K-AKT pathway. The odontogenic fibroma in this patient was positive for mTOR, suggesting that the development of the odontogenic fibroma was the result of abnormal activation of mTOR, as in angiofibroma. The clinical course of this patient is presented and the developmental mechanism of central odontogenic fibroma is discussed.

Cherubism is a rare autosomal dominant condition affecting the jaws and caused by mutations in the gene encoding for the adapter protein SH3BP2 that maps to chromosome 4p16.3. Cherubism is characterized by symmetrically developing bone lesions in the maxilla and mandible. The lesions have been radiographically and histopathologically well-described. Here, we present a family with cherubism with two of its members featuring odontogenic tumorous proliferations in association with persistent central giant cell lesions (CGCL). Specifically, the proband, a 25-year-old male, developed a radiolucent lesion characterized histologically by central odontogenic fibroma-like proliferation in association with a CGCL component, while his mother, at age 57, was diagnosed with primary intraosseous odontogenic carcinoma with areas of benign fibro-osseous lesions. In both patients the lesions occurred in the anterior mandible and presented with clinical enlargement. The son underwent incisional biopsy and did not have additional treatment. His mother underwent extensive mandibulectomy due to widespread tumor. The son has two affected children with classic cherubism while a third child at age 5, had not shown any features of the disease. Mutation analysis of three affected members resulted in the identification of a heterozygous mutation in SH3BP2 (c.1244G>C; p.Arg415Pro). To the best of our knowledge, association of cherubism with odontogenic neoplastic lesions has hitherto not been reported in the literature, thus suggesting a relationship between cherubism with disturbed odontogenesis.

Amelogenesis Imperfecta (AI) is a hereditary enamel defect which is characterized by developmental abnormalities in the quantity and/ or quality of enamel. This condition has been associated with dental anomalies, including taurodontism, congenitally missing teeth, delayed eruption, crown resorption, pulpal calcifications and odontogenic fibromas. This paper presents two cases of AI which were associated with multiple impacted permanent teeth in both the cases; and pulpal calcifications and pericoronal odontogenic fibromas of W.H.O type additionally, in one of the cases.

OBJECTIVE: Langerhans cell (LC) is an antigen-presenting cell that is very important for T-cell-mediated immune reactions. Our previous studies have shown the presence of LCs in some odontogenic tumors and cysts. In this study, we further examined the presence of LCs in odontogenic epithelia of 16 odontogenic fibromas (OFs).
METHODS: Anti-CD1a and anti-S-100 immunostains were used to detect the presence of LCs in nests or strands of odontogenic epithelia of 16 OFs.
RESULTS: These 16 OFs included 10 peripheral OFs excised from seven male and three female patients (mean age, 38 years) and six central OFs (including one recurrent OF) removed from five male patients (mean age, 28 years). Of the 10 peripheral OFs, six were found on the mandibular gingiva and four on the maxillary gingiva. Four central OFs were located in the maxilla and two in the mandible. We found that both anti-CD1a and anti-S-100 immunostains had an equal ability to identify LCs in OFs. Positively stained dendritic LCs could be detected in nests and strands of odontogenic epithelia in nine (six peripheral and three central OFs) of the 16 OFs. In five peripheral OFs, dendritic LCs were found in occasional nests or strands of odontogenic epithelia. In one peripheral and three central OFs, dendritic LCs could be detected in at least half of the nests or strands of odontogenic epithelium in the tissue section.
CONCLUSIONS: LCs can be detected in the nests or strands of odontogenic epithelia in approximately 60% of the 10 peripheral OFs and approximately 50% of the six central OFs detected.