Immunohistochemical and genetic analysis of respiratory epithelial adenomatoid hamartomas and seromucinous hamartomas: are they precursor lesions to sinonasal low-grade tubulopapillary adenocarcinomas?

Respiratory epithelial adenomatoid hamartoma (REAH) and seromucinous hamartoma (SH) are rare tumor-like lesions of the nasal cavity, paranasal sinuses, and nasopharynx. The pathogenesis of REAH/SH is still unclear. Neoplastic proliferation, chronic mechanical irritation, inflammation, or possible embryological tissue misplacement are speculated as possible mechanisms of their development. Low-grade tubulopapillary adenocarcinoma (LGTA) is a rare variant of nonsalivary, nonintestinal type sinonasal adenocarcinoma. The aim of this study was to evaluate the immunohistochemical and genetic profiles of 10 cases of REAH/SH, with serous, mucinous, and respiratory components evaluated separately and to compare these findings with the features of 9 cases of LGTA. All cases of REAH/SH and LGTA were analyzed immunohistochemically with a cocktail of mucin antigens (MUC1, MUC2, MUC4, MUC5AC, MUC6) and with epithelial (CK7, CK20, CDX2, SATB2) and myoepithelial markers (S100 protein, p63, SOX10). The next-generation sequencing assay was performed using FusionPlex Solid Tumor Kit (ArcherDx) in 10 cases of REAH/SH, and the EGFR-ZNF267 gene fusion was detected in 1 of them. Two female REAH/SH cases were assessed for the presence of clonality. Using the human androgen receptor assay, 1 case was proved to be clonal. The serous component of REAH/SH was positive for CK7/MUC1 and SOX10 similarly to LGTA. Although REAH/SH and LGTA are histopathologically and clinically separate entities, the overlap in their morphological and immunohistochemical profiles suggests that REAH/SH might be a precursor lesion of LGTA.

Expression and clinical significance of LRRC4 in benign and malignant nasopharyngeal diseases.

The aim of this study was to investigate the expression of LRRC4 in nasopharyngeal carcinomas, nasopharyngeal precancerous lesions, and nasopharyngitis as well as the clinical significance of LRRC4. Fifty patients with nasopharyngeal carcinoma were selected as study subjects; 28 patients with chronic nasopharyngitis and 22 patients with nasopharyngeal precancerous lesions served as controls. Immunohistochemical analysis was used to study protein expression of LRRC4; the relation between LRRC4 expression and the clinical stage and histopathological features of nasopharyngeal carcinoma was also analyzed. The LRRC4 expression manifested itself as yellow staining in the cytoplasm or nucleus. LRRC4 was strongly expressed in nasopharyngeal epithelial tissues of patients with chronic nasopharyngitis and in nasopharyngeal precancerous lesions; the rates of positive results were 82.1 and 81.8%, respectively. LRRC4 was weakly expressed in nasopharyngeal carcinoma tissues, at a rate of 10% positive results (P< 0.001); there was no significant difference in the expression of LRRC4 among different clinical stages and pathological grades. Therefore, disappearance of LRRC4 expression is a major feature of nasopharyngeal carcinoma.

Expression of GRIN2A in benign and malignant nasopharyngeal diseases and its clinical significance.

The gene glutamate receptor, ionotropic, N-methyl D-aspartate 2A (GRIN2A) is associated with development and neuron viability, and our previous studies showed it to be substantially methylated in nasopharyngeal carcinoma, indicating a link to this disease. The aim of this work was to investigate GRIN2A expression and its clinical significance in nasopharyngeal carcinoma, in contrast to nasopharyngitis and nasopharyngeal precancerous lesions. Fifty patients with nasopharyngeal carcinoma were selected as study subjects, while 28 chronic nasopharyngitis patients and 22 individuals with nasopharyngeal precancerous lesions were used as controls. Immunohistochemical analysis was used to study GRIN2A protein expression, and its relationship with nasopharyngeal carcinoma clinical stage and histopathological features were assessed. GRIN2A appeared as yellow staining in the cytoplasm or nucleus. It was strongly expressed in the nasopharyngeal epithelial tissues of patients with chronic nasopharyngitis and in nasopharyngeal precancerous lesions, the proportions of GRIN2A-positive cells being 82.1 and 72.7%, respectively. However, it was weakly expressed in nasopharyngeal carcinoma tissues, with 28.0% of cells testing positive (P < 0.001). No significant difference in the expression of GRIN2A was observed between different clinical stages and pathological grades. We conclude that weak GRIN2A expression is a major feature of nasopharyngeal carcinoma.

Spontaneous proliferative lesions in the nasopharyngeal meatus of F344 rats.

Spontaneous proliferative lesions in the nasopharyngeal meatus were identified as the cause of death in 12 of 1,600 male and 5 of 1,600 female Fisher 344 (F344) rats used in 2-yr carcinogenicity studies; none of the lesions were considered treatment related. All the rats showed dyspnea, abdominal distension, and clinical deterioration. Gross features were characterized by simultaneous occurrence of conspicuous gaseous distension of the intestinal tract, especially in the ileum and cecum, and focal nodular lesions in the nasopharyngeal meatus. Histopathologically, the nasopharyngeal meatus was partially obstructed by the following proliferative lesions: 3 areas of hyperplasia of the ectopic sebaceous glands in the soft and hard palate, 4 areas of squamous metaplasia (SM) with massive hyperkeratosis, 5 squamous cell papillomas (SCPs), and 5 squamous cell carcinomas (SCCs). No pathological changes were found in the distended portion of the intestinal tract. Formalin-fixed, paraffin-embedded samples of the proliferative lesions from the nasopharyngeal meatus were examined for the presence of mutations in the c-H-ras and c-K-ras genes. In vitro amplification of DNA using a polymerase chain reaction was combined with a nonisotopic method for selective oligonucleotide hybridization. Two of the 4 SM lesions, 3 of the 5 SCPs, and 5 of the 5 SCCs contained 1-3 point mutations in the c-H-ras and/or c-K-ras gene. Immunohistochemically, overexpression of p53 protein was found in 1 area of SM with a dysplastic lesion and 2 SCCs. These findings indicate that detailed examination of the upper respiratory system, including the nasopharyngeal meatus, may be particularly helpful for identifying primary occult lesions in F344 rats that show only gut distension at necropsy in long-term toxicity studies. In addition, mutations of the ras genes may be an important step in the early stages of carcinogenesis in the rat nasopharyngeal meatus, whereas p53 mutations could occur relatively late.

[Expression of cytotoxic-granule-associated protein TIA-1 in nasal NK/T cell lymphomas and lymphoid hyperplasia].

OBJECTIVE: 27 cases of nasal NK/T cell lymphomas were studied for the expression of the cytotoxic-granule-associated protein TIA-1, its immunophenotype, genotype and Epstein-Barr virus infection status. METHODS: Immunohistochemical staining for TIA-1, CD3, CD56, CD45RO, CD8, CD20; polymerase chain reaction (PCR) for TCR gamma chain gene and immunoglobulin JH chain gene rearrangement analysis; in situ hybridization for EBER 1/2 and double staining for TIA-1, CD8 with EBER 1/2. 10 cases of lymphoid hyperplasia were used for comparison. RESULTS: (1) In the 27 cases of nasal NK/T cell lymphomas, most tumor cells expressed TIA-1, CD3, CD45RO and EBER 1/2; expression of CD56 was found in 26 cases; no CD8 or CD20 were detected in tumors cells of this series of cases. Double labelled staining showed that the TIA-1 positive tumor cells coexpress EBER 1/2. TCR gamma chain gene rearrangement was detected in only 1 of the 27 cases. (2) In the 10 cases of lymphoid hyperplasia of nasal pharynx, a small amount of TIA-1 positive cells were present in 8 cases and their distribution similar to that of CD8+ cells, in 4 of these cases a few EBER 1/2+ cells were detected, the number of CD45RO+ cells and CD20+ cells were similar in all 10 cases. Double labelled staining showed that the EBER 1/2+ cells did not coexpress TIA-1. CONCLUSION: A high percentage of these tumor cells express TIA-1 and correlate with that of CD56, CD3 epsilon, CD45RO and EBER1/2 in nasal NK/T cell lymphomas. It is suggested that expression of TIA-1 in this tumor may be related to the tumor origin and may also be responsible for its special biologic behavior.