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A case of S-100 negative melanoma: A diagnostic pitfall in the workup of a poorly differentiated metastatic tumor of unknown origin

When confronted with a metastatic poorly differentiated tumor of unknown origin, the initial workup includes the standard panel of immunostains to rule out carcinoma, sarcoma, lymphoma, and the greatest mimicker in pathology – malignant melanoma. Although not specific, the S-100 protein is expressed...

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Autores principales: Biernacka, Anna, Linos, Konstantinos D., DeLong, Peter A., Suriawinata, Arief A., Padmanabhan, Vijayalakshmi, Liu, Xiaoying
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Medknow Publications & Media Pvt Ltd 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5040106/
https://www.ncbi.nlm.nih.gov/pubmed/27729935
http://dx.doi.org/10.4103/1742-6413.190914
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author Biernacka, Anna
Linos, Konstantinos D.
DeLong, Peter A.
Suriawinata, Arief A.
Padmanabhan, Vijayalakshmi
Liu, Xiaoying
author_facet Biernacka, Anna
Linos, Konstantinos D.
DeLong, Peter A.
Suriawinata, Arief A.
Padmanabhan, Vijayalakshmi
Liu, Xiaoying
author_sort Biernacka, Anna
collection PubMed
description When confronted with a metastatic poorly differentiated tumor of unknown origin, the initial workup includes the standard panel of immunostains to rule out carcinoma, sarcoma, lymphoma, and the greatest mimicker in pathology – malignant melanoma. Although not specific, the S-100 protein is expressed in over 95% of malignant melanomas. Herein, we present a case of multiorgan metastatic malignancy with a dominant hilar and mediastinal mass in a current smoker; clinically, highly suggestive of widespread primary lung cancer. This case was eventually classified as malignant melanoma, despite a significant diagnostic challenge due to lack of prior history, unusual cytomorphology, and S-100 protein negativity. A battery of immunostains was performed and the addition of other melanocytic-associated markers confirmed the melanocytic lineage of the neoplasm. This case highlights the pitfalls in the differential diagnosis of a metastatic tumor of unknown origin by fine needle aspiration cytology due to the significant morphologic overlap of poorly differentiated malignancies. We emphasize that, albeit rare, malignant melanomas can be completely negative for S-100 protein and the use of additional melanocytic-associated markers in the differential workup maybe critical in arriving promptly at a proper diagnosis. We also briefly discuss other currently available immunohistochemical markers that can assist in the identification of the S-100 negative melanoma.
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spelling pubmed-50401062016-10-11 A case of S-100 negative melanoma: A diagnostic pitfall in the workup of a poorly differentiated metastatic tumor of unknown origin Biernacka, Anna Linos, Konstantinos D. DeLong, Peter A. Suriawinata, Arief A. Padmanabhan, Vijayalakshmi Liu, Xiaoying Cytojournal Case Report When confronted with a metastatic poorly differentiated tumor of unknown origin, the initial workup includes the standard panel of immunostains to rule out carcinoma, sarcoma, lymphoma, and the greatest mimicker in pathology – malignant melanoma. Although not specific, the S-100 protein is expressed in over 95% of malignant melanomas. Herein, we present a case of multiorgan metastatic malignancy with a dominant hilar and mediastinal mass in a current smoker; clinically, highly suggestive of widespread primary lung cancer. This case was eventually classified as malignant melanoma, despite a significant diagnostic challenge due to lack of prior history, unusual cytomorphology, and S-100 protein negativity. A battery of immunostains was performed and the addition of other melanocytic-associated markers confirmed the melanocytic lineage of the neoplasm. This case highlights the pitfalls in the differential diagnosis of a metastatic tumor of unknown origin by fine needle aspiration cytology due to the significant morphologic overlap of poorly differentiated malignancies. We emphasize that, albeit rare, malignant melanomas can be completely negative for S-100 protein and the use of additional melanocytic-associated markers in the differential workup maybe critical in arriving promptly at a proper diagnosis. We also briefly discuss other currently available immunohistochemical markers that can assist in the identification of the S-100 negative melanoma. Medknow Publications & Media Pvt Ltd 2016-09-20 /pmc/articles/PMC5040106/ /pubmed/27729935 http://dx.doi.org/10.4103/1742-6413.190914 Text en Copyright: © 2016 Biernacka, et al.; Licensee Cytopathology Foundation Inc. http://creativecommons.org/licenses/by-nc-sa/3.0 This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
spellingShingle Case Report
Biernacka, Anna
Linos, Konstantinos D.
DeLong, Peter A.
Suriawinata, Arief A.
Padmanabhan, Vijayalakshmi
Liu, Xiaoying
A case of S-100 negative melanoma: A diagnostic pitfall in the workup of a poorly differentiated metastatic tumor of unknown origin
title A case of S-100 negative melanoma: A diagnostic pitfall in the workup of a poorly differentiated metastatic tumor of unknown origin
title_full A case of S-100 negative melanoma: A diagnostic pitfall in the workup of a poorly differentiated metastatic tumor of unknown origin
title_fullStr A case of S-100 negative melanoma: A diagnostic pitfall in the workup of a poorly differentiated metastatic tumor of unknown origin
title_full_unstemmed A case of S-100 negative melanoma: A diagnostic pitfall in the workup of a poorly differentiated metastatic tumor of unknown origin
title_short A case of S-100 negative melanoma: A diagnostic pitfall in the workup of a poorly differentiated metastatic tumor of unknown origin
title_sort case of s-100 negative melanoma: a diagnostic pitfall in the workup of a poorly differentiated metastatic tumor of unknown origin
topic Case Report
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5040106/
https://www.ncbi.nlm.nih.gov/pubmed/27729935
http://dx.doi.org/10.4103/1742-6413.190914
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