Micropapillary clusters in early-stage lung adenocarcinomas

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Abstract
BACKGROUND It is known that patients who have pulmonary adenocarcinomas with a pathologic micropapillary pattern (pMPP) featuring small papillary tufts that lack a central fibrovascular core have a poor prognosis. Although the pMPP initially was identified in surgical material, preoperative detection is desirable from the standpoint of making treatment decisions. Therefore, the authors focused on cytologic features resembling the pMPP in lung adenocarcinomas, with particular reference to the survival of patients with pathologic Stage I disease. METHODS The authors reviewed clinical course data, preoperative cytologic specimens, and histologic materials from 110 patients with Stage I adenocarcinoma of the lung who presented between 1986 and 1995. Cytology of micropapillary clusters (MPCs) was characterized by round, 3-dimensional, cohesive clusters of neoplastic cells (consisting of > 3 cells and < 20 cells) with a pseudopapillary configuration. Total counts of cohesive clusters that consisted of more than three neoplastic cells on slides and frequencies of MPCs were investigated. RESULTS All patients (54 females and 56 males) had a preoperative diagnosis of malignancy and underwent complete surgical resection. The patients with Stage I disease were subclassified into an MPC-positive group (n = 41) and an MPC-negative group (n = 69). The 5-year survival rate was 91.3% for patients in the MPC-negative group and 75.6% for patients in the MPC-positive group; this difference was statistically significant. CONCLUSIONS MPC cytology is a distinct prognostic marker for early-stage lung adenocarcinoma with poor prognosis. The presence of this component, therefore, should alert the clinician to the need for close follow-up. Cancer (Cancer Cytopathol) 2004. © 2004 American Cancer Society.