Napsin A es una proteinasa aspártica funcional que se expresa en los neumocitos tipo II del parénquima pulmonar normal y en los túbulos contorneados proximales del riñón. Su expresión en los carcinomas pulmonares varía en los distintos tipos histológicos. Se ha descrito positividad citoplásmica granular en más del 90% de los adenocarcinomas primarios de pulmón, siendo negativos el carcinoma escamoso y el carcinoma de célula pequeña. El adenocarcinoma pulmonar con diferenciación entérica es una excepción, puesto que no expresa Napsin A.

En ovario, contribuye al diagnóstico diferencial entre carcinoma de células claras (88-100%), carcinoma seroso y endometrioide.

También se ha descrito positividad con Napsin A en carcinomas renales, especialmente en los subtipos de células claras (17-75%) y papilar (43-80%).

Los carcinomas de mama, páncreas, tracto biliar y colon raramente son positivos.

 

BIBLIOGRAFÍA

 

• Hirano T, Gong Y, Yoshida K, et al. Usefulness of TA02 (napsin A) to distinguish primary lung adenocarcinoma from metastatic lung adenocarcinoma. Lung Cancer. 2003;41:155–162.
• Chuman Y, Bergman AC, Ueno T, et al. Napsin A, a member of the aspartic family, is abundantly expressed in normal lung and kidney tissue and is expressed in lung adenocarcinoma. FEBS Lett. 1999;26;462(1-2): 129–134.
• Dejmek A, Naucler P, Smedjeback A, et al. Napsin A (TAO2) is a useful alternative to thyroid transcription factor-1 (TTF1) for the identification of pulmonary adenocarcinoma cells in pleural effusion. Diagn Cytopathol. 2007;35:493–497.
• Kadivar M, Boozari B. Applications and limitations of immunohistochemical expression of “Napsin-A” in distinguishing lung adenocarcinoma from adenocarcinomas of other organs. Appl Immunohistochem Mol Morphol. 2013;21(3):191-5.
• Argani P, Hicks J, De Marzo AM, et al. Xp11 translocation renal cell carcinoma (RCC): extended immunohistochemical profile emphasizing novel RCC markers. Am J Surg Pathol 2010;34:1295–303.
• Bishop JA, Sharma R, Illei PB. Napsin A and thyroid transcription factor-1 expression in carcinomas of the lung, breast, pancreas, colon, kidney, thyroid, and malignant mesothelioma. Hum Pathol 2010;41:20–25.
• Stoll LM, Johnson MW, Gabrielson E, et al. The utility of napsin-A in the identification of primary and metastatic lung adenocarcinoma among cytologically poorly differentiated carcinomas. Cancer Cytopathol 2010;118:441–449.
• Ye J, Findeis-Hosey JJ, Yang Q, et al. Combination of napsin A and TTF-1 immunohistochemistry helps in differentiating primary lung adenocarcinoma from metastatic carcinoma in the lung. Appl Immunohistochem Mol Morphol 2011;19:313–317.
• Ordóñez NG. Value of PAX8, PAX2, napsin A, carbonic anhydrase IX, and claudin-4 immunostaining in distinguishing pleural epithelioid mesothelioma from metastatic renal cell carcinoma. Mod Pathol. 2013;26(8):1132-43.
• Kandalaft PL, Gown AM and Isacson C. The Lung-Restricted Marker Napsin A Is Highly Expressed in Clear Cell Carcinomas of the Ovary. Am J Clin Pathol 2014;142:830-836.

 

11-2014 /  M. Verdú