Bone metastasis of papillary thyroid carcinoma simulating a pulmonary origin. Unusual immunohistochemistry leading to misdiagnosis / Metástasis ósea de cáncer papilar de tiroides simulando un origen pulmonar. Inmunohistoquímica inusual que conduce a un diagnóstico equívoco

Immunophenotypical features from tumors can be variable and, sometimes, confusing. We herein report a 61 year old woman with two foci of papillary thyroid microcarcinoma who developed a bone lesion four months after total thyroidectomy/central lymphadenectomy (mpT1aN0), with an immunohistochemical pattern suggestive of a pulmonary rather than a thyroid origin (CK7, napsin-A and TTF1 positive; and negative thyroglobulin). Further biomarkers (HBME-1 and PAX8) were performed in order to confirm primary tumor, leading to conclusion of a bone metastasis from thyroid papillary carcinoma. We believe it is always advisable to perform more than one biomarker as part of a panel to get a more reliable diagnosis

Las características inmunofenotípicas de los tumores pueden ser variables y, a veces, confusas. Reportamos el caso de una mujer de 61 años con 2 focos de microcarcinoma papilar de tiroides, que desarrolló una lesión ósea a los 4 meses de practicarse tiroidectomía total/linfadenectomía central (mpT1aN0), con patrón inmunohistoquímico sugerente de origen pulmonar en lugar de tiroideo (CK7, napsina-A y TTF1 positivos, y tiroglobulina negativa). Se analizaron biomarcadores adicionales (HBME-1 y PAX8) para confirmar el tumor primario, llegándose a la conclusión de metástasis ósea por cáncer papilar de tiroides. Creemos que es siempre recomendable analizar más de un biomarcador como parte de un panel, para obtener un diagnóstico más fiable

Bone metastasis of papillary thyroid carcinoma simulating a pulmonary origin. Unusual immunohistochemistry leading to misdiagnosis.

Immunophenotypical features from tumors can be variable and, sometimes, confusing. We herein report a 61 year old woman with two foci of papillary thyroid microcarcinoma who developed a bone lesion four months after total thyroidectomy/central lymphadenectomy (mpT1aN0), with an immunohistochemical pattern suggestive of a pulmonary rather than a thyroid origin (CK7, napsin-A and TTF1 positive; and negative thyroglobulin). Further biomarkers (HBME-1 and PAX8) were performed in order to confirm primary tumor, leading to conclusion of a bone metastasis from thyroid papillary carcinoma. We believe it is always advisable to perform more than one biomarker as part of a panel to get a more reliable diagnosis.