Misleading images of ductal carcinoma in situ: 4 lymph nodes with metastasis / Imágenes equívocas de carcinoma ductal in situ: 4 ganglios linfáticos con metástasis

Since sentinel lymph node examination became routine, findings of benign ectopic breast tissue in lymph nodes have increased. We report images of ductal carcinoma in situ (DCIS) in four lymph nodes in a 76-year-old woman with bilateral breast carcinoma. The right lumpectomy showed intermixed invasive lobular and ductal carcinoma, plus DCIS. 19 nodes were isolated in the axillary lymphadenectomy, 4 of which displayed solid and cribriform DCIS. Myosin and p63 immunohistochemical techniques were positive, suggesting an erroneous diagnosis of “metastatic DCIS”. A further three cases of DCIS in lymph nodes have been previously reported, all with a distinct layer of myoepithelial cells with actin, myosin or p63. Biologically, these images of DCIS in lymph nodes are not credible and three major hypotheses have been proposed to explain these findings: Iatrogenic Mechanical Transport, Revertant DCIS, and primary DCIS of lymph nodes. We consider the first one the most plausible explanation. Our case is unique as several, rare findings are simultaneously observed. More new cases, together with additional immunohistochemical techniques and molecular testing on previous cases, are needed to find a definitive explanation of this histologic finding.(AU)

A partir del uso rutinario del examen del ganglio centinela, los hallazgos de tejido mamario ectópico son frecuentes. Presentamos los hallazgos de carcinoma ductal in situ (CDIS) en 4 ganglios linfáticos en una mujer de 76 años con carcinoma de mama bilateral. La lumpectomía derecha mostró una mezcla de patrones de carcinomas ductal y lobular infiltrante, además de CDIS. De los 19 ganglios aislados, 4 mostraron patrones cribiformes y sólidos de CDIS. La miosina y la p63 fueron positivas, sugiriendo un diagnóstico erróneo de «CDIS metastático». En la literatura se han comunicado 3 casos adicionales de patrones de CDIS en ganglios linfáticos, mostrando capa periférica de células mioepiteliales positivas para actina, miosina o p63. Desde un punto de vista biológico, estos hallazgos de CDIS en ganglios linfáticos son discutibles, proponiéndose 3 hipótesis para explicarlo: transporte mecánico yatrogénico, CDIS revertido y CDIS primario de ganglio linfático. Creemos que la primera alternativa es la más plausible. Nuestro caso es único al mostrar, de modo conjunto, diversos hallazgos infrecuentes. El estudio de nuevos casos, así como la aplicación de técnicas inmunohistoquímicas y moleculares a casos de archivo, arrojarían datos que permitirían llegar a una explicación definitiva de este hallazgo histológico.(AU)

Misleading images of ductal carcinoma in situ: 4 lymph nodes with metastasis.

Since sentinel lymph node examination became routine, findings of benign ectopic breast tissue in lymph nodes have increased. We report images of ductal carcinoma in situ (DCIS) in four lymph nodes in a 76-year-old woman with bilateral breast carcinoma. The right lumpectomy showed intermixed invasive lobular and ductal carcinoma, plus DCIS. 19 nodes were isolated in the axillary lymphadenectomy, 4 of which displayed solid and cribriform DCIS. Myosin and p63 immunohistochemical techniques were positive, suggesting an erroneous diagnosis of "metastatic DCIS". A further three cases of DCIS in lymph nodes have been previously reported, all with a distinct layer of myoepithelial cells with actin, myosin or p63. Biologically, these images of DCIS in lymph nodes are not credible and three major hypotheses have been proposed to explain these findings: Iatrogenic Mechanical Transport, Revertant DCIS, and primary DCIS of lymph nodes. We consider the first one the most plausible explanation. Our case is unique as several, rare findings are simultaneously observed. More new cases, together with additional immunohistochemical techniques and molecular testing on previous cases, are needed to find a definitive explanation of this histologic finding.