Napsin A expression in pulmonary sclerosing haemangioma

Benign tumours of the bronchopulmonary system

The vast majority of tumours arising in the bronchopulmonary system are malignant in nature. Benign tumours of the lung are relatively rare and are often incidental findings during clinical investigations for unrelated conditions. These lesions can arise in the bronchial tree or the pulmonary parenchyma and may be of epithelial, mesenchymal, salivary gland-type or unknown differentiation. Although the spectrum of these lesions is wide, the clinical, pathological and immunohistochemical characteristics of the most relevant will be the subject of this review. In addition, the most important features allowing differentiation from malignant pulmonary neoplasms will be discussed.

Molecular Genetic Landscape of Sclerosing Pneumocytomas

OBJECTIVES

Sclerosing pneumocytomas are rare pulmonary neoplasms that are typically benign. However, rare patients experience progressive disease, and therapy targeting specific genetic underpinnings could be an attractive therapeutic option. Recent studies have found recurrent AKT 1 mutations in sclerosing pneumocytoma, but little is known about whether oncogenic fusion genes may also be present.

METHODS

To better understand the genetic background, 10 sclerosing pneumocytomas were subjected to next-generation sequencing cancer mutation panel testing (n = 9) and/or RNA sequencing (n = 3). The patients were all women (average age, 47 years; range, 17-74 years).

RESULTS

Eight patients had solitary sclerosing pneumocytomas, while one had two tumors, and one had many bilateral tumors. Recurrent mutations were noted in genes involved in the mTOR pathway, including AKT1, PIK3R1, and PTEN. AKT1 alterations were particularly common, present in 78%. No recurrent genetic fusions were identified. The patient in our study with multiple bilateral lesions was treated with the mammalian target of rapamycin (mTOR) inhibitor everolimus, with no objective radiographic evidence of treatment response after 4 months.

CONCLUSIONS

Our data further support that abnormal activation of the mTOR pathway is a consistent genetic event in sclerosing pneumocytoma. This warrants further exploration to determine if mTOR pathway inhibitors may be effective in patients with metastatic or recurrent disease.

Pulmonary sclerosing pneumocytoma, a rare tumor of the lung

Pulmonary sclerosing pneumocytoma (PSP) is a rare benign pulmonary tumor. Usually diagnosed incidentally by chest X-ray or chest CT scan. We presented a case of PSP in a 50-year-old woman who was diagnosed with a nodular lesion in the right lung. Thoracotomy was used for the excision of the mass. Pathologic examination revealed no malignant cells. Immunohistochemical studies were performed. TTF-1 was (+), Napsin-A was found to be weakly (+). After surgical resection, the patient was followed up.

Pulmonary papillary adenoma presenting in central portion: a case report

Pulmonary papillary adenoma is a very rare tumor usually presenting in periphery of the lung. Herein, we present a case of pulmonary papillary adenoma located in central portion of the lung in a 17 year-old Chinese female. A well-defined mass was incidentally detected at right pulmonary hilar region by imaging examination. Histologically, the tumor is predominantly composed of abundant papillary structures lined by columnar to cuboidal epithelial cells resembling type II pneumocytes. Immunohistochemical staining showed that the epithelial cells were diffusely positive for cytokeratin, cytokeratin7, TTF-1, EMA, surfactant apoprotein A, Napsin A, P63 and β-catenin. The Ki-67 proliferation index was approximately 2 %. Based on morphologic features and the immunohistochemical profile, the tumor was consistent with pulmonary papillary adenoma. Thus, it should be noted that pulmonary papillary adenoma was also a possible diagnosis for a central mass.

Napsin A is a specific marker for ovarian clear cell adenocarcinoma

Ovarian clear cell adenocarcinoma has a relatively poor prognosis among the ovarian cancer subtypes because of its high chemoresistance. Differential diagnosis of clear cell adenocarcinoma from other ovarian surface epithelial tumors is important for its treatment. Napsin A is a known diagnostic marker for lung adenocarcinoma, and expression of napsin A is reported in a certain portion of thyroid and renal carcinomas. However, napsin A expression in ovarian surface epithelial tumors has not previously been examined. In this study, immunohistochemical analysis revealed that in 71 of 86 ovarian clear cell adenocarcinoma patients (83%) and all of the 13 patients with ovarian clear cell adenofibroma, positive napsin A staining was evident. No expression was observed in 30 serous adenocarcinomas, 11 serous adenomas or borderline tumors, 19 endometrioid adenocarcinomas, 22 mucinous adenomas or borderline tumors, 10 mucinous adenocarcinomas, or 3 yolk sac tumors of the ovary. Furthermore, expression of napsin A was not observed in the normal surface epithelium of the ovary, epithelia of the fallopian tubes, squamous epithelium, endocervical epithelium, or the endometrium of the uterus. Therefore, we propose that napsin A is another sensitive and specific marker for distinguishing ovarian clear cell tumors (especially adenocarcinomas) from other ovarian tumors.

Napsin-A, TTF-1, EGFR, and ALK Status Determination in Lung Primary and Metastatic Mucin-Producing Adenocarcinomas

Pulmonary mucin-producing adenocarcinomas may be indistinguishable on conventional histology from a metastasis, as thyroid transcription factor-1 (TTF-1) expression often is lacking and KRAS mutations are widely present even in extrapulmonary sites. Few data have been reported on the diagnostic role of napsin-A and epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK) gene alterations in this challenging differential diagnosis. Seventy-seven surgically resected cases, including 53 primary and 24 metastatic tumors from different sites, were evaluated for napsin-A, TTF-1, and ALK by immunohistochemistry and for EGFR mutations by direct sequencing. Overall, napsin-A expression in primary lung mucin-producing adenocarcinomas was 36% (8% mucinous, 17% colloid, 87.5% solid, and 100% signet ring cell) and TTF-1 expression reached an overall figure of 42% (12.5% mucinous, 33% colloid, 87.5% solid, and 100% signet ring cell). Metastatic mucinous adenocarcinomas did not react with napsin-A or with TTF-1. All primary and metastatic tumors lacked EGFR mutations, while a single case of signet ring cell lung adenocarcinoma showed ALK expression and rearrangement at fluorescent in situ hybridization analysis. Napsin-A has a lower sensitivity compared with TTF-1 in primary mucin-producing adenocarcinomas of the lung. However, both antibodies have an absolute specificity, being always negative in metastatic mucinous adenocarcinomas. EGFR mutations and ALK translocation or expression are exceedingly rare in mucin-producing adenocarcinomas of the lung, resulting unnecessary as diagnostic tool in this setting.