Bronchiolar Adenoma/Pulmonary Ciliated Muconodular Papillary Tumor

Abstract

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.

The 2021 WHO Classification of Lung Tumors: Impact of Advances Since 2015

“…In particular, for proximal-type BA/ CMPT, with prominent mucinous features and peripheral skip lesions, the differential diagnosis includes IMA. The challenge of distinguishing CMPT/BA from adenocarcinoma, especially IMA, during intraoperative consultation has been highlighted in several studies, 176,185,186 because the presence of cilia and basal cells may be subtle in frozen sections.…”

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

“…A total of 134 BA/CMPT lesions were found in the literature from 2010 to 2021; 53 BAs in nine reports (nine lesions were excluded because of duplicates, and 13 lesions that did not meet the definition of BA wereexcluded, 3,[28][29][30][33][34][35][36][37] and 81 CMPTs in 26 reports (11 lesions were excluded because of duplicates). [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][20][21][22][23][24][25][26][27]31,32 Of these, 94 (70.1%) were interpreted as proximal-type BA, and 25 (18.6%) were interpreted as distal-type BA, whereas 15 lesions (11.1%) could not be categorized as either of them.…”

“…Bronchiolar adenomas grow slowly and are usually detected when they are small. To date, no recurrence has been reported, 3–37 and its excellent prognosis suggests that BA is a benign tumor. The majority of BAs have driver mutations including BRAF V600E, unusual EGFR exon 19 deletions (e.g.…”

Ciliated muconodular papillary tumor of the lung with cavitary change: A case report with 11‐year preoperative follow‐up

“…6 It is challenging to distinguish CMPT from mucinous adenocarcinomas in frozen slides because of the abundant mucous lakes and the difficulty in recognizing ciliated columnar cells in the small floating cells. 6,7 However, CMPT does not represent nuclear atypia or mitotic activity, as against mucinous adenocarcinoma. 8,9 A distinctive molecular feature of the tumor is a single driver mutation.…”

“…Occasionally, the tumor has been misdiagnosed as a mucinous adenocarcinoma on intraoperative frozen section analysis. Shirsat et al reported that only 16.7% of cases were diagnosed as CMPT during intraoperative frozen studies 6 . It is challenging to distinguish CMPT from mucinous adenocarcinomas in frozen slides because of the abundant mucous lakes and the difficulty in recognizing ciliated columnar cells in the small floating cells 6,7 .…”