Ciliated muconodular papillary tumors of the lung: Cytologic features and diagnostic pitfalls in intraoperative examinations

Ciliated muconodular papillary tumor of the lung: a case report and literature review

Background

Ciliated Muconodular Papillary Tumor (CMPT) was first reported in 2002, and fewer than 100 cases have since been reported. The prognosis after surgical resection is good, and recurrence has not been reported. However, it is easily misdiagnosed as adenocarcinoma. Summarizing the CT features of CMPT will help doctors better understand the disease.

Case presentation

Here, we report a rare and interesting case of ciliated muconodular papillary tumor. A 6-mm diameter solid nodule with slight lobulation, short spines, and subpleural indentation. Patients with clinical diagnosis of high-risk subpleural nodule in the left lung underwent thoracoscopic surgery. Most CMPT cases lack specific clinical manifestations and were found incidentally on physical examination or during a workup for other diseases. The disease was diagnosed through CT and biopsy, and it responded well to surgery.

Conclusions

This paper presents the detailed computed tomography features of CMPT to help prevent misdiagnosis. The typical manifestations of CMPT imaging as solid and partial nodules, nodules in subpleural or peripheral zones, and nodules contain cavities.

A clinicopathologic and molecular analysis of five cases of bronchiolar adenoma with rare mutations

Bronchiolar adenoma (BA) is a rare benign lung tumor that shows proliferation of bland bronchiolar-type epithelium containing a continuous layer of basal cells. This tumor entity has been newly added to the recent World Health Organization (WHO) classification 5th edition. This entity encompasses a spectrum of lesions: the classic ciliated muconodular papillary tumor (CMPT) and the non-classic CMPT. Although BA is reported to have driver mutations including BRAF V600E, EGFR, and KRAS, the molecular profile of BA is still incompletely understood. Five resected BAs at our institutions were analyzed. The BA lesions were subdivided into two groups: three proximal-type BAs and two distal-type BAs. NRAS codon 12/13 mutation and EML4 exon 20-ALK exon 20 fusion were found in two of the three proximal-types. BRAF V600E mutation was found in one of the two distal-types. Two cases coexisted with lung adenocarcinoma, with EGFR exon 19 deletion and KRAS mutation, respectively. No recurrence was observed at a median of 12 months (range 2-84 months) of follow-up. BA has uncommon variants of mutation seen in lung adenocarcinoma. NRAS mutation and ALK fusion partner has not been reported previously. The present cases may reinforce the distinctive biology of BA from lung adenocarcinoma.

Atypia in pulmonary cytology: Morphologic spectrum and causes

BACKGROUND

The term "atypical" has had a long history of usage in cytology but has had variable definitions and usage. Most commonly the term was used to indicate a degree of cytomorphologic abnormality greater than that clearly due to reactive or reparative changes but not associated with a high concern on the part of the cytopathologist that a malignancy is present. The Papanicolaou Society of Cytopathology System for Reporting Respiratory Cytology provided a foundation for using the category "Atypical" along with the category "Suspicious for Malignancy" to categorize the spectrum of morphologic changes ranging from those which are clearly benign to those that are clearly malignant. The two intermediate categories of "Atypical" and "Suspicious for Malignancy" have characteristic recommendations resulting in clinical utility for both categories.

CONCLUSION

The Papanicolaou Society of Cytopathology System for Reporting Respiratory Cytology represents a useful system with defined intermediate categories of Atypical and Suspicious for Malignancy.

[Diagnosis and treatment of benign lung tumors]

Benign lung tumors account 2-12% of all lung neoplasms. The classification of lung tumors, adopted by the World Health Organization in 2015, is reported with a detailed indication of all changes based on immunohistochemical and genetic studies. Diagnosis with computed tomography, dynamic and perfusion computed tomography, virtual bronchoscopy and positron emission tomography is described. These methods ensure 94-98% sensitivity for differentiation with malignancies. CT and ultrasound signs of benign tumors are presented. Surgical strategy for newly diagnosed nodes in the lungs is analyzed depending on their dimensions and risk factors. It was shown that comprehensive examination with possible surgical verification of the diagnosis is necessary for nodes over 6 mm and moderate-to-high risk factors. The authors describe argon plasma and laser destruction, bronchoplastic procedures for central benign tumors, thoracoscopy for peripheral neoplasms. One can conclude that high-tech methods of radiological and nuclear diagnosis are valuable to determine benign neoplasms and their dimensions with a high degree of reliability. Endoscopic and thoracoscopic procedures are successfully used for benign tumors.

Bronchiolar Adenoma/Pulmonary Ciliated Muconodular Papillary Tumor

OBJECTIVES

To describe the histologic features that are helpful in the diagnosis of the rare bronchiolar adenomas/ciliated muconodular papillary tumors (BAs/CMPTs) during intraoperative consultation.

METHODS

Multi-institutional retrospective review of frozen sections of 18 BAs/CMPTs.

RESULTS

In 14 of 18 cases, BA/CMPT was the primary reason for sublobar lung resection, and in 4 cases, BA/CMPT was an incidental finding intraoperatively for resections performed for carcinoma in other lobes. There were 11 proximal-type/classic BAs/CMPTs and 7 distal-type/nonclassic BAs/CMPTs. Only 3 (16.7%) of 18 were correctly diagnosed at the time of frozen section, all of which were proximal type/classic. The remainder were diagnosed as adenocarcinoma (n = 7); invasive mucinous adenocarcinoma (n = 1); non-small cell lung carcinoma (n = 1); cystic mucinous neoplasm, favor adenocarcinoma (either mucinous or colloid type) (n = 1); favor adenocarcinoma, cannot exclude CMPT (n = 1); atypical proliferation (n = 2); mucinous epithelial proliferation (n = 1); and mucous gland adenoma (n = 1).

CONCLUSIONS

BA/CMPT can potentially be misdiagnosed as carcinoma during intraoperative consultation. On retrospective review of the frozen sections, the presence of the following may help to avoid misdiagnosis: a mixture of bland ciliated columnar cells, mucinous cells, and, most important, a basal cell layer, as well as a lack of necrosis, significant atypia, and mitoses.

Distal-type bronchiolar adenoma of the lung harboring an EGFR exon 21 p.L858R mutation: A case report

Here, we present a case of a distal‐type bronchiolar adenoma (BA) of the lung. BAs are benign lung tumors characterized by nodular proliferation of bilayered bronchiolar‐type epithelium with a continuous layer of basal cells. This patient underwent S3 segmentectomy following detection by computed tomography (CT) scan of a gradually enlarging ground‐glass nodule (GGO) over a five month period. Nodule morphology and immunophenotype were consistent with those of distal‐type BA of the lung. An epidermal growth factor receptor (EGFR) exon 21 p.L858R missense mutation was identified which, to the best of our knowledge, is the first case to be reported of a common gene mutation associated with non‐small cell lung cancer (NSCLC) being found in a BA lesion. Following surgery, the patient remains relapse‐free.

Key points

Significant findings of the study

Pathological assessment of a lung nodule confirmed a papillary tumor with a double‐layered cell structure, less than typical cytoplasm, and a mixture of ciliated columnar and globular cells, consistent with a distal‐type bronchiolar adenoma.

What this study adds

This is the first report of an EGFR exon 21 p.L858R mutation in a bronchiolar adenoma.

Distal-type bronchiolar adenoma of the lung expressing p16INK4a - morphologic, immunohistochemical, ultrastructural and genomic analysis - report of a case and review of the literature

Bronchiolar adenoma (BA) of the lung is a rare benign neoplasm. Because of a chest abnormal shadow indicated by health checkup, a 77-year-old female nonsmoker underwent computed tomography, revealing an 8 mm ground glass nodule in the peripheral field of the right lower lobe. Wedge resection of the nodule was performed, with a frozen diagnosis of primary lung adenocarcinoma. The localized, 8 × 4 × 3 mm-sized, jelly-like mass microscopically revealed a lepidic-growing lesion composed of ciliated columnar cells, mucous cells and basal cells surrounded by mucin pool. Neither nuclear atypia nor mitotic activity was noted. Immunohistochemically, the ciliated, mucous and basal cells were positive for TTF-1 and p16^INK4a . Mucous cells were positive for napsin A and focally expressed MUC5AC. MUC6 was negative. Basal cells were positive for CK5/6, p40, p63 and podoplanin. Human papillomavirus genome was undetectable by in situ hybridization. Ultrastructurally, the bronchiolar epithelial tubules consisted of two layers, the inner nonciliated microvillous cells and the outer basal-like cells, and some of the inner cells were filled with mucin granules in cytoplasm. Molecular analysis of the tumor failed to show driver mutations. The final diagnosis was distal-type BA. The postoperative course was uneventful for 6 months.

Ciliated muconodular papillary tumor of the lung: report of two cases and review of the literature

Ciliated muconodular papillary tumor (CMPT) is a peripheral non-endobronchial lung nodule, consisting of ciliated columnar cells and goblet cells with basaloid cell proliferation. Only about 50 cases confirmed by surgery have been reported in English literature worldwide. We present two surgical cases of CMPT in this report. Two patients presented with abnormal computed tomography findings but no obvious symptoms. The first patient's intraoperative frozen examination was unable to distinguish benignity from malignancy, and he received lobectomy. The other patient's intraoperative frozen examination indicated adenocarcinoma, but she received wedge resection for her refusal to lobectomy. The two patients' postoperative pathological analysis finally confirmed the diagnosis of CMPT. We believe that our cases may be essential for pathologists and surgeons to improve their understanding.