Hyperplastic fibro-epithelial lesions are the most common tumor-like swellings in the mouth. The neodymium yttrium aluminium garnet (Nd:YAG) laser appears to be useful for the surgical treatment of these lesions. Some controversies of laser surgery concern the accuracy of pathological diagnosis as well as the control of thermal damage on the target tissue. The aim of this study was to establish if the thermal changes induced by the Nd:YAG laser may affect the histopathological diagnosis and the evaluation of the resection margins. Furthermore, we compared the histological features of oral benign fibro-epithelial lesions excised through Nd:YAG laser and traditional scalpel. Twenty-six benign fibro-epithelial oral lesions from 26 patients, localized in the same oral subsites (cheek and buccal mucosa), were collected at the Unit of Oral Pathology and Oral Laser-assisted Surgery of the Academic Hospital of the University of Parma, Italy. Specimens were subclassified into three groups according to the tool used for the surgical excision. Group 1 included six specimens excised through Nd:YAG laser with an output power of 3.5 W and a frequency of 60 Hz (power density 488,281 W/cm2); Group 2 included nine specimens excised through Nd:YAG laser with an output power of 5 W and a frequency of 30 Hz; Group 3 included 11 specimens excised through a Bard-Parker scalpel blade no. 15c. Epithelial changes, connective tissue modifications, presence of vascular modifications, incision morphology and the overall width of tissue modification were evaluated. Differences between specimens removed with two different parameters of Nd:YAG laser were not significant with regard to stromal changes (p=0.4828) and vascular stasis (p=0.2104). Analysis of regularity of incision revealed a difference which was not statistically significant (p=1.000) between group 1 and group 2. Epithelial and stromal changes were significantly more frequent in specimens with a mean size less than 7 mm (p<0.0001). Nd:YAG laser induced serious thermal effects in small specimens (mean size less than 7 mm) independently from the frequency and power employed. The quality of incision was better and the width of overall tissue injuries was less in the specimens obtained with higher frequency and lower power (group 1: Nd:YAG laser at 3.5 W and 60 Hz).

Myoepithelial carcinoma of salivary glands is an underrecognized and challenging entity with a broad morphologic spectrum, including an EWSR1-rearranged clear cell variant. Myoepithelial carcinoma is generally aggressive with largely unknown genetic features. A retrospective review of Salivary Gland Tumor Registry in Pilsen searching for the key words “clear cell myoepithelial carcinoma,” “hyalinizing clear cell,” and “clear cell malignant myoepithelioma” yielded 94 clear cell myoepithelial carcinomas (CCMCs) for molecular analysis of EWSR1 rearrangement using fluorescence in situ hybridization (FISH). Tumors positive for EWSR1 gene rearrangement were tested by next-generation sequencing (NGS) using fusion-detecting panels. NGS results were confirmed by reverse-transcription polymerase chain reaction or by FISH. Twenty-six tumors originally diagnosed as CCMC (26/94, 27.6%) revealed split signals for EWSR1 by FISH. Six of these tumors (6/26, 23%) displayed amplification of the EWSR1 locus. Fifteen cases were analyzable by NGS, whereas 9 were not, and tissue was not available in 2 cases. None of the CCMCs with EWSR1 rearrangements detected by FISH had an EWSR1 fusion transcript. Fusion transcripts were detected in 6 cases (6/15, 40%), including LIFR-PLAG1 and CTNNB1-PLAG1, in 2 cases each, and CHCHD7-PLAG1 and EWSR1-ATF1 fusions were identified in 1 case each. Seven cases, including those with PLAG1 fusion, were positive for PLAG1 rearrangement by FISH, with notable exception of CHCHD7-PLAG1, which is an inversion not detectable by FISH. One single case with EWSR1-ATF1 fusion in NGS showed ATF1 gene rearrangement by FISH and was reclassified as clear cell carcinoma (CCC). In addition, another 4 cases revealed ATF1 rearrangement by FISH and were reclassified as CCC as well. Moreover, 12/68 (17%) CCMCs with intact EWSR1 gene were selected randomly and analyzed by NGS. PLAG1 fusions were found in 5 cases (5/12, 41.6%) with LIFR (2 cases), FGFR1 (2 cases), and CTNNB1 (1 case) as partner genes. Overall, PLAG1 gene rearrangements were detected in 10/38 (26%) tested cases. None of the tumors had SMARCB1 loss by immunohistochemistry as a possible explanation for the EWSR1 abnormalities in FISH. Novel findings in our NGS study suggest that EWSR1-FISH positive CCMC is a gene fusion-driven disease with frequent oncogenic PLAG1 fusions, including LIFR-PLAG1 and CTNNB1-PLAG1 in most cases. Productive EWSR1 fusions are found only in a minority of EWSR1-ATF1-rearranged cases, which were in part reclassifiable as CCCs. Detectable EWSR1-FISH abnormality in CCMCs without gene fusion perhaps represents a passenger mutation with minor or no oncologic effect.

The peripheral ossifying fibroma (POF) is a relatively uncommon, reactive gingival overgrowth usually composed of cellular fibroblastic tissue containing one or more mineralized tissues, namely bone, cementum-like material, or dystrophic calcification. The aetiology and pathogenesis of POF are yet not clear, but some authors have hypothesized a reaction originating from the periodontal ligament, as a result of irritating agents such as dental calculus, plaque, orthodontic appliances, and ill-fitting restorations. The aim of our study was to report the clinicopathologic features of a case series of POF from a single Italian institution. A total of 27 cases were collected over an 18-year period. Detailed relevant medical history, clinical and histological information were recorded for each patient. The age range of patients (m = 6; f = 21) was 17.2-80.1 years with a mean of 42.9 ± 18.1 years. Occurrence of the lesion in the mandibular and maxillary arches was similar, and 67.0% occurred in the incisor-cuspid region. The lesions ranged in size from 0.3 to 5.0 cm (mean, 1.3 cm ± 1.1 cm). All the different types of mineralization were present, with higher prevalence of lamellar bone. The lesions were treated by surgical excision and four lesions in three patients recurred after surgery. Surgeons should consider the high recurrence rate of POF and remove the lesion down to the bone involving also the adjacent periosteum and the periodontal ligament. Professional prophylaxis should precede any surgical procedure, and periodical dental hygiene recalls are important in order to remove any possible irritating factor.

Fine-needle aspiration biopsy represents the most reliable test for cytologic evaluation of thyroid nodules. However, inadequate samples may occur leading to a repetition of the procedure with the consequence of patients' discomfort and poor compliance. In this paper, we present results from biopsy of thyroid nodules obtained by combining: (1) ultrasound (US) guidance, (2) no-aspiration technique, and (3) on-site review of specimens. A total of 465 nodules were biopsied in 307 patients. Solitary nodules and multinodular goiter were present in 36.8% and 63.1% of patients, respectively. After collection, each sample was smeared in duplicates, one of which was stained with hematoxylin and checked on-site by a cytopathologist. In cases of inadequate smears, biopsies were immediately repeated. All slides were then processed for final cytologic results, which were reported as benign in 427 nodules (91.8%), malignant in 12 nodules (2.5%), with follicular proliferation or suspicious for malignancy in 23 nodules (4.9%). Inadequate final cytology was reported in 3 nodules (0.6%). No statistically significant relationship was found between nodule size and adequacy of specimens. We conclude that the combination of US guidance, capillary collection with no-aspiration technique, and on-site review of slides, characterizes an advantageous method for thyroid nodule fine-needle biopsy.

Oncocytic mucoepidermoid carcinoma (OMEC) is a rare but diagnostically challenging variant of mucoepidermoid carcinoma (MEC). OMEC is notable for differential diagnostic considerations that are raised as a result of overlap with other benign and low-grade oncocytic salivary gland tumors. Diffuse and strong immunoreactivity of p63 protein may be useful in distinguishing OMEC from its mimics. However, focal p63 staining can be present in benign oncytomas. Presence of mucin-containing cells, mucinous cystic formation, and foci of extravasated mucin are considered a hallmark of MEC. True mucocytes may be, however, very few and hardly discernable in OMECs. Recent evidence has shown that most MECs harbor gene fusions involving MAML2. A retrospective review of archived pathology files and the authors’ own files was conducted to search for “low-grade/uncertain oncocytic tumor,” “oncocytoma,” and “oncocytic carcinoma” in the period from 1996 to 2019. The tumors with IHC positivity for p63 and/or p40, and S100 negativity, irrespective of mucicarmine staining, were tested by next-generation sequencing using fusion-detecting panels to detect MAML2 gene rearrangements. Two index cases from consultation practice (A.S. and A.A.) of purely oncocytic low-grade neoplasms without discernible mucinous cells showed a CRTC1-MAML2 fusion using next-generation sequencing, and were reclassified as OMEC. In total, 22 cases of oncocytic tumors, retrieved from the authors’ files, and from the Salivary Gland Tumor Registry, harbored the MAML2 gene rearrangements. Presence of mucocytes, the patterns of p63 and SOX10 immunopositivity, and mucicarmine staining were inconsistent findings. Distinguishing OMEC devoid of true mucinous cells from oncocytoma can be very challenging, but it is critical for proper clinical management. Diffuse and strong positivity for p63 and visualization of hidden mucocytes by mucicarmine staining may be misleading and does not always suffice for correct diagnosis. Our experience suggests that ancillary studies for the detection of MAML2 rearrangement may provide useful evidence in difficult cases.