Early-Stage Lung Adenocarcinomas With a Micropapillary Pattern, a Distinct Pathologic Marker for a Significantly Poor Prognosis

Abstract

Adenocarcinomas with a micropapillary pattern (MPP), featuring small papillary tufts lacking a central fibrovascular core, are thought to have a poor prognosis. To examine whether the MPP is a predictor of prognosis, clinicopathologic characteristics of adenocarcinomas were analyzed with particular reference to survival of early-stage patients. The subjects were 344 consecutive patients (female/male ratio 163:181) for whom complete surgical resection was undertaken at the Cancer Institute Hospital, Japan, during 1986-1995. Histologically, they were divided into two groups: MPP-positive (n = 139; 40%) and MPP-negative (n = 205; 60%). The following items were significantly more frequent in the MPP-positive group: metastasis to lymph nodes (p <0.001), pleural invasion (p = 0.02), intrapulmonary metastasis (p <0.001), and nonsmoking status (p = 0.002). In stage I patients (i.e., without lymph node metastasis, n = 154), 5-year survival of the MPP-positive group (n = 45) was 79%, significantly lower than the MPP-negative group (n = 109) of 93% (p = 0.004). In many cases of the c-stage I MPP-positive group, upstaging was necessary on the basis of pathologic findings for metastases, and the survival was between stage I and stage II. Our study clearly indicated that the MPP is a distinct prognostic marker for lung adenocarcinoma, particularly regarding apparent stage I diseases.

Micropapillary pattern and grade of stromal invasion in pT1 adenocarcinoma of the lung: usefulness as prognostic factors

“…Micropapillary pattern is characterized by papillary structures with tufts lacking a central fibrovascular core. 12 Patients with micropapillary patternpositive lung adenocarcinomas have poor prognosis and tend to present with extensive lymph node involvement and metastatic disease, [12][13][14][15] similar to patients with micropapillary carcinomas of the breast, 23 urinary bladder, 24,25 ureter 26,27 and parotid gland. 28,29 However, little is known about the mechanisms involved in micropapillary patternassociated lymph node metastasis.…”

“…In contrast, lung adenocarcinomas with a micropapillary pattern have been reported to have a worse biological behavior, and that the patients with micropapillary pattern tend to present with advanced stage including lymph node metastasis. [12][13][14][15] In the present study, we investigated whether the stromal invasion grading system correlates with prognosis including pT1 (r3.0 cm) adenocarcinomas. Furthermore, we also tested whether the stromal invasion grade 3 could be subclassified into two groups that show significantly different prognoses based on the presence and absence of micropapillary pattern.…”

Histopathological features and prognostic significance of the micropapillary pattern in lung adenocarcinoma

“…The micropapillary pattern was defined according to the two previous studies; 18,19 it was identified as small tufts lying in alveolar spaces or in spaces encased within thin walls of connective tissue, and the tufts had no fibrovascular core. The extent of the micropapillary pattern was subclassified as none (0% of the tumor), focal (o10%), moderate (o50%), or extensive (Z50%) based on the proportion of micropapillary pattern area in the tumors.…”

“…[8][9][10][11][12] Recently, a pathological entity called the micropapillary pattern has been reported to have worse outcomes in breast, 13 colon, 14 urinary tract, 15 ovary, 16 salivary gland, 17 and lung 18,19 cancer. The micropapillary pattern in lung adenocarcinoma is characterized by small papillary tufts lying in alveolar spaces or in spaces encased by connective tissues, with the tufts having no fibrovascular core, 18,19 and it has been reported as an important factor for poor prognosis. [18][19][20][21] However, the detailed histopathobiological features of the micropapillary pattern have not yet been clarified.…”

“…The micropapillary pattern in lung adenocarcinoma is characterized by small papillary tufts lying in alveolar spaces or in spaces encased by connective tissues, with the tufts having no fibrovascular core, 18,19 and it has been reported as an important factor for poor prognosis. [18][19][20][21] However, the detailed histopathobiological features of the micropapillary pattern have not yet been clarified. We investigated the histological, immunohistochemical, electron microscopic, and clinicopathological properties of the micropapillary pattern to elucidate why it could be a factor in poor prognoses.…”