title: Micropapillary component in lung adenocarcinoma: a distinctive histologic feature with possible prognostic significance.
abstract: Micropapillary carcinoma or a micropapillary carcinoma component has been reported in the ovary, breast, and urinary bladder and is generally thought to have prognostic significance. However, little has been written on micropapillary differentiation in lung carcinoma. We studied 35 cases of primary lung adenocarcinoma with a micropapillary component seen at the M.D. Anderson Cancer Center. The micropapillary component in these tumors ranged from focal to prominent and was seen at both primary and metastatic sites. This component was not associated with any particular histologic subtype of lung adenocarcinoma. Of the 15 cases with available material, 14 (93%) stained positive for cytokeratin 7, whereas only two of the 15 cases (13%) stained positive for cytokeratin 20. Thyroid transcription factor-1 immunostaining of tumor nuclei was seen in 12 of the 15 cases (80%). Immunostaining was seen in areas both with and without micropapillary differentiation. Thirty-three of 35 patients (94%) developed metastases, which occurred most commonly in the lymph nodes (n = 26), and also in the lung (n = 17), brain (n = 9 cases), bone (n = 9 cases), and other sites. Most metastases had a prominent micropapillary component, irrespective of the extent of the micropapillary carcinoma component in the primary lung tumor. Adequate clinical follow-up information was available for 29 patients. The mean follow-up was 25 months. At their last follow-up, 16 of 29 patients (55%) were still alive with disease, 5 (17%) were dead of disease, and 8 (28%) were alive with no evidence of disease. We believe that a micropapillary component occurring in lung adenocarcinoma should be reported, as this component may be more likely to metastasize. The presence of this component should alert the clinician to search more carefully for metastases and have a closer follow-up on these patients. It is also important to recognize this component in evaluating a metastasis from an unknown primary site, as it should alert the pathologist to a possible primary in the lung in addition to breast, urinary bladder, and ovary.
authors.affiliation: Department of Pathology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: Mitual B
authors.initials: MB
authors.lastname: Amin
authors.forename: Pheroze
authors.initials: P
authors.lastname: Tamboli
authors.forename: Shakil H
authors.initials: SH
authors.lastname: Merchant
authors.forename: Nelson G
authors.initials: NG
authors.lastname: Ordóñez
authors.forename: Jungsil
authors.initials: J
authors.lastname: Ro
authors.forename: Alberto G
authors.initials: AG
authors.lastname: Ayala
authors.forename: Jae Y
authors.initials: JY
authors.lastname: Ro
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001842:Bone and Bones / Q000737:chemistry; D002291:Carcinoma, Papillary / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000032:analysis; D008175:Lung Neoplasms / Q000473:pathology*; D008198:Lymph Nodes / Q000737:chemistry; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009687:Nuclear Proteins / Q000032:analysis; D011379:Prognosis; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors / Q000032:analysis
chemical_list: C000614412:NKX2-1 protein, human; D009687:Nuclear Proteins; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors; D007633:Keratins