Ciliated muconodular papillary tumor of the lung: A newly defined peripheral pulmonary tumor with conspicuous mucin pool mimicking colloid adenocarcinoma: A case report and review of literature

Abstract

We report the case of a 68-year-old man with a newly defined rare entity of a peripheral pulmonary tumor, consisting of a nodular papillary lesion with papillary structures containing ciliated columnar and goblet cells, as well as floating tumor cells in the mucin pool. The conspicuous mucin pool was observed to be mimicking colloid adenocarcinoma in a low-power view, particularly in a frozen section slide. We originally reported it as an adenocarcinoma during intraoperative consultation. Immunohistochemically, the tumor cells exhibited a similar immunophenotype to pulmonary adenocarcinoma, except for the presence of focal ciliated and basaloid cells, which we found using CK5/6 and P63 immunostaining. No KRAS or EGFR mutation was found. We revised the diagnosis to that of a ciliated muconodular papillary tumor (CMPT). Four years after a wedge resection, the patient remained free of tumors. Although the malignant potential of CMPT cannot be ignored, a wedge resection with a safe margin might be a treatment option for CMPT patients.

Ciliated Muconodular Papillary Tumors of the Lung

“…A similar indolent clinical course was documented in all reported CMPTs. [1][2][3][4][5] A benign nature for CMPT is readily implied histologically, not only by the constant presence of cilia, but also by bland cytology, the lack of mitotic figures, and the consistent basal cell population. Nonetheless, the longterm biological behavior of CMPTs could not be established by the present study with a limited follow-up, and further data need to be collected to draw solid conclusions.…”

“…[1][2][3][4][5] CMPTs are small peripheral nonendobronchial lung nodules arising in middle-aged and older asymptomatic patients. Often incidentally discovered by CT screening, CMPTs commonly receive a radiologic interpretation of adenocarcinoma owing to the peripheral location and irregular contour.…”

“…Ten cases with characteristic features of CMPT as described in the literature [1][2][3][4][5] were identified between 2006 and 2014. The clinical and pathologic records were reviewed, and a histologic analysis of the resected specimens was performed.…”

“…In addition, variable terminologies have been proposed for histologically similar, if not identical, tumors, including "solitary peripheral ciliated glandular papillomas," "mucinous adenomatous hyperplasia," and "peripheral pulmonary papillary/glandular neoplasms with ciliated cells," [6][7][8][9][10] and their relationship to CMPTs is poorly understood. Furthermore, the great majority of these reports originated from East Asia, [1][2][3][4][5][6][8][9][10] and these ciliated lesions do not seem to have received global attention.…”

“…The tumor showed an indolent course and nonatypical cytologic properties, so the authors suspected that CMPTs represented a benign neoplasm. Only 5 similar tumors have been subsequently reported as CMPTs in the English-language literature, [2][3][4][5] but its clinicopathologic features have not been analyzed in a sizable series. In addition, variable terminologies have been proposed for histologically similar, if not identical, tumors, including "solitary peripheral ciliated glandular papillomas," "mucinous adenomatous hyperplasia," and "peripheral pulmonary papillary/glandular neoplasms with ciliated cells," [6][7][8][9][10] and their relationship to CMPTs is poorly understood.…”