Salivary Gland-type Tumors of the Lung

Salivary gland-type cancers: cross-organ demographics of a rare cancer

BACKGROUND

Salivary gland-type cancers (SGTCs) are histologically heterogeneous and can affect organs other than the salivary glands. Some tumors outside the salivary glands are diagnosed on their unique histological characteristics. Comprehensive cross-organ studies on SGTCs are limited.

METHODS

We retrospectively analyzed the data of patients with salivary duct carcinoma (SDC), adenoid cystic carcinoma (AdCC), mucoepidermoid carcinoma (MEC), epithelial-myoepithelial carcinoma (EMC), acinic cell carcinoma (AcCC), and polymorphous adenocarcinoma (PAC) who visited our institution between 2009 and 2019. The primary tumor sites were classified into four categories; major salivary glands, head/neck (H/N) excluding (exc) major salivary glands (MSG) regions, broncho-pulmonary regions, and "others". H/N exc MSG was further divided into three subcategories, nasal/paranasal sinus, oral and pharynx/larynx.

RESULTS

We identified 173 patients with SGTCs, with SDC, AdCC, MEC, EMC, AcCC, and PAC accounting for 20%, 42%, 27%, 3%, 8%, and 1% of the cases, respectively. The most frequent primary site was the major salivary glands (64%), followed by H/N exc MSG regions (27%), broncho-pulmonary regions, and "others", thus non-salivary gland origins accounted for 9% of all cases. Patients with SDC, MEC, AcCC, or SGTC of the major salivary glands and broncho-pulmonary regions were more frequently treated by surgery. The overall survival time of the patients with MEC was significantly better than that of patients with SDC or EMC.

CONCLUSIONS

This cross-organ study highlights the clinical significance of SGTCs, underscoring the need for developing novel therapies for this rare disease entity.

Evolving Diagnostic Approach of Pulmonary Salivary Gland-type Tumors

Pulmonary salivary gland-type, although bear resemblance to their salivary gland counterparts, present a diagnostic challenge due to their rarity. Clinical features overlap with lung carcinoma; however, management strategies and outcomes are distinct. Onus falls on the pathologist to avoid misinterpretation of small biopsies especially in young, nonsmokers with slow growing or circumscribed endobronchial growths. A combination of cytokeratin, myoepithelial immunohistochemical markers, and identification of signature molecular alteration is invaluable in differentiation from lung cancers and subtyping the pulmonary salivary gland-type tumor.

Current diagnosis and treatment of salivary gland-type tumors of the lung

Salivary gland-type tumors of the lung are thought to originate from the submucosal exocrine glands of the large airways. Due to their rare occurrence, reports of their study are limited to small-scale or case reports. Therefore, daily clinical practices often require a search for previous reports. In the last 20 years, several genetic rearrangements have been identified, such as MYB::NF1B rearrangements in adenoid cystic carcinoma, CRTC1::MAML2 rearrangements in mucoepidermoid carcinoma, EWSR1::ATF1 rearrangements in hyalinizing clear cell carcinoma and rearrangements of the EWSR1 locus or FUS (TLS) locus in myoepithelioma and myoepithelial carcinoma. These molecular alterations have been useful in diagnosing these tumors, although they have not yet been linked to molecularly targeted therapies. The morphologic, immunophenotypic, and molecular characteristics of these tumors are similar to those of their counterparts of extrapulmonary origin, so clinical and radiologic differential diagnosis is required to distinguish between primary and metastatic disease of other primary sites. However, these molecular alterations can be useful in differentiating them from other primary lung cancer histologic types. The management of these tumors requires broad knowledge of the latest diagnostics, surgery, radiotherapy, bronchoscopic interventions, chemotherapy, immunotherapy as well as therapeutic agents in development, including molecularly targeted agents. This review provides a comprehensive overview of the current diagnosis and treatment of pulmonary salivary gland tumors, with a focus on adenoid cystic carcinoma and mucoepidermoid carcinoma, which are the two most common subtypes.

SALTT study: A retrospective analysis of 111 SAlivary gland tumors of Lung and Tracheobronchial Tree

INTRODUCTION

Primary pulmonary salivary gland-type tumours (PPSGT) are rare lung neoplasms arising from submucosal seromucinous glands in the central airway.

METHODS AND RESULTS

We retrospectively analysed the clinicopathological features of 111 PPSGTs diagnosed at our institute between 2003 and 2021. The mean age at diagnosis was 43.8 years(range 6-78 years) and a male-to-female ratio of 2:1. On imaging, 92 % of cases had centrally located tumours and 37.3 % were early stage. The histopathological types included 70 cases (63 %) of mucoepidermoid carcinoma (MEC), 31 cases (27.7 %) of adenoid cystic carcinoma (ADCC), two cases of myoepithelial carcinoma, one case each of acinic cell carcinoma (ACC), clear cell carcinoma (CCC), epithelial myoepithelial carcinoma (EMC) and 5 others [including adenocarcinoma of minor salivary gland origin(n = 3), carcinoma with sebaceous differentiation(n = 1) and poorly differentiated carcinoma of salivary gland type(n = 1)]. The size of the tumours found in the resection specimens ranged from 1 cm to 13 cm, with an average size of 4.9 cm. High-risk attributes such as lymphovascular invasion (LVI), perineural invasion (PNI), pleural involvement, positive resection margins, and nodal metastasis were identified in 15.3 %, 15.3 %, 13.6 %,15.2 % and 6.7 % of cases, respectively. These attributes were found to be more frequent in ADCC than in MEC. Surgery was the main treatment modality [68/84 (80 %) cases]. ADCC cases had more recurrence and distant metastasis than MEC cases. The 3- year overall-survival (OS) and recurrence-free survival(RFS) were better in patients with age lesser than 60 years(p-value <0.0001), low pT stage (p-value 0.00038) and lower grade of MEC(p-value-0.0067).

CONCLUSION

It is crucial to have an acquaintance with the morphologic spectrum and immunophenotypic characteristics of PPSGT to recognize them in this unusual location. In tandem, it is crucial to differentiate them from conventional primary non-small cell lung carcinoma, as the management protocols and prognostic implications differ significantly.

A Curious Case of Clear Cell Morphology in a Patient with Lung Cancer: Diagnostic Challenges

An 82-year-old woman with COPD presented to the emergency department with cough, increasing sputum production, wheezing, and worsening shortness of breath for two weeks. On imaging studies, the patient was found to have a right upper lobe spiculated nodule and an endobronchial lesion with near total occlusion of the right lower lobe bronchus with sub-segmental atelectasis. Bronchoscopy with EBUS-TBNA of subcarinal and right hilar lymph nodes revealed lung cancer with clear cell phenotype. Given the predominance of clear cell morphology, the diagnosis of metastatic renal or ovarian cancer was entertained. However, there was no evidence of renal or ovarian lesions on the PET-CT scan, ruling out the possibility. Salivary gland type lung cancer (STLC), which is responsible for less than 1% of all lung cancer cases in adults, was also considered. The two distinct STLCs that may have similar morphologic appearances are hyalinizing clear cell carcinoma (HCCC) and mucoepidermoid carcinoma (MEC). The other type of tumour in the lung that demonstrates a clear cell phenotype is perivascular epithelioid cell neoplasms or PEComa, which are mesenchymal in origin. Immunohistochemical staining was strongly positive for p63, CK5/6, CK7, CK-LMW, and negative for TTF-1, Napsin A, p16, and CK20. Additional staining, including HMB-45, S-100, and mucicarmine, were also negative. Next-generation sequencing for the salivary gland fusion panel, including EWSR1-ATF1 fusion and EWSR1 gene rearrangement for HCCC and MAML2 gene rearrangements for MEC, was negative. She was diagnosed with non-small cell lung cancer favouring squamous cell carcinoma with clear cell phenotype, a rare entity.

Targeted therapy for rare lung cancers: Status, challenges, and prospects

Lung cancer causes the most cancer-related deaths worldwide. In recent years, molecular and immunohistochemical techniques have rapidly developed, further inaugurating an era of personalized medicine for lung cancer. The rare subset of lung cancers accounts for approximately 10%, each displaying distinct clinical characteristics. Treatments for rare lung cancers are mainly based on evidence from common counterparts, which may lead to unsolid clinical benefits considering intertumoral heterogeneity. The increasing knowledge of molecular profiling of rare lung cancers has made targeting genetic alterations and immune checkpoints a powerful strategy. Additionally, cellular therapy has emerged as a promising way to target tumor cells. In this review, we first discuss the current status of targeted therapy and preclinical models for rare lung cancers, as well as provide mutational profiles by integrating the results of existing cohorts. Finally, we point out the challenges and future directions for developing targeted agents for rare lung cancer.

Primary acinic cell carcinoma of the trachea: A case report and literature review

RATIONALE

Salivary gland-type acinic cell carcinoma (ACC) is a low-grade malignancy. Primary ACC of the trachea and lungs is rare; here, we describe 1 such case. The histological morphology of tracheal ACC was similar to that of its salivary gland-associated equivalent. Because of its rarity, it is easily misdiagnosed as another type of tracheal or lung tumor. Microscopic analysis of pathological features and immunohistochemistry help diagnose primary ACC of the trachea and lungs.

PATIENT CONCERNS

A 33-year-old female complained of shortness of breath and hemoptysis for 2 years, and reported the symptoms to have aggravated over the last 4 months. The patient was admitted to our hospital for further treatment. Enhanced computed tomography revealed a soft tissue density nodule shadow in the trachea, which was approximately 1.3 × 1.2 cm in size.

DIAGNOSES

Based on the clinical information, morphological features, and immunohistochemistry, the pathological diagnosis was primary ACC of the trachea.

INTERVENTION

The tracheal lesion was resected with an electric snare, electrotomy, freezing, and an argon knife using a rigid bronchoscope.

OUTCOMES

The patient's postoperative course was uneventful.

LESSONS

It is important to prevent misdiagnosis of this type of tumor as another type of lung tumor. Morphological and immunohistochemical features can be useful in diagnosing primary ACC of the trachea and lungs.

Clinical, laboratory, pathological, and radiological characteristics and prognosis of patients with pulmonary salivary gland-type tumors

PURPOSE

Primary pulmonary salivary gland-type tumor (PSGT) included two main subtypes, pulmonary adenoid cystic carcinoma (PACC) and pulmonary mucoepidermoid carcinoma (PMEC). The purpose of this study was to compare the similarities and differences between these two subtypes and to identify independent risk factors for the prognosis of PSGT patients.

METHODS

This study screened patients with a pathological diagnosis of PSGT in Beijing Chaoyang Hospital between 2010 and 2021. The clinical, pathological, radiological, laboratory test, and other characteristics were collected, and t, nonparametric and chi-squared tests were used to compare the differences in clinical characteristics of the two subtypes. COX univariate and multivariate analyses were used to explore prognostic-related risk factors.

RESULTS

A total of 62 patients with PSGT were included in our center over a 12-year period. There were 26 PMEC patients and 36 PACC patients. There were differences in the clinical, pathological, and radiological features of the two tumor subtypes. Univariate analysis showed that weight loss, chemotherapy, white blood cells, lymphocytes, red blood cells, total protein, and total bilirubin might be related to the prognosis in PSGT patients. Multivariate results showed that lymphocytes (p = 0.031), red blood cells (p = 0.047), total protein (p = 0.032), and total bilirubin (p = 0.010) were independent prognostic risk factors. Chemotherapy (HR 4.452; 95% CI 1.723-11.503; p = 0.002) might be associated with progression-free survival (PFS).

CONCLUSION

The two subtypes of PSGT had significantly different clinical, laboratory, pathological, and radiological features. However, there was no significant difference in the prognosis of patients with PMEC and PACC subtypes. Cox univariate and multivariate analyses showed that levels of lymphocytes, erythrocytes, total protein and total bilirubin in the peripheral blood of PSGT patients might be related to patient overall survival. Chemotherapy might also be associated with PFS.

Pulmonary Sialadenoma Papilliferum and Its Mimics: What You Need to Know

Pulmonary salivary gland-type tumors (SGT) represent a small but distinct group of primary lung neoplasms. These types of tumors originate from the submucosal bronchial glands of the tracheobronchial tree. Pulmonary SGTs differ greatly in the incidence of individual tumors from salivary gland tumors of the head and neck. Additionally, the vast majority of pulmonary SGT are malignant. Recently, pathologic diagnosis has significantly improved with the application of molecular diagnostic technologies. However, the current knowledge of benign SGTs is limited; moreover, tumor diversity and overlapping morphological features of SGT represent diagnostic challenges such as correct tumor categorization and their accurate differentiation from malignant lesions. Compounding this inherent difficulty has been the recent introduction of new variants, including sialadenoma papilliferum (SP). Pulmonary SP is very rare, with limited reports available, and most of the initial diagnoses rendered so far were incorrect, resulting in inappropriate treatment. Several cases of SP have recently been reported. This review will serve to update practicing pathologists on the morphology, immunophenotype, and molecular characteristics of SP and its mimics.