RESUMEN
Se presentan los resultados multidisciplinarios de cuatro casos de mioepiteliomas de glándula salival diagnosticados por biopsia por aspiración con aguja fina y resecados posteriormente. Histológicamente dos casos fueron benignos y dos malignos. Los extendidos celulares de las variedades benignas contenían una población uniforme de células discretamente alargados con citoplasma bipolar y membranas celulares conspicuas. El núcleo fue pequeño y oval con cromatina homogénea. Las células se disponían en grupos y nidos sobre un fondo proteináceo. Se observaron células aisladas adyacentes que presentaban citoplasma eosinófilo, granular y claro con núcleo central, redondo e hipercromático. En uno de los extendidos se observó numerosos capilares con células endoteliales prominentes y fondo con matrix condroide. Dos casos presentaron cambios citológicamente malignos con un fondo necrohemorrágico, pleomorfismo, nucléolo prominente, hipercromatismo y mitosis atípicas ocasionales. Las reacciones de inmunohistoquímica demostraron positividad para proteína S-100 y vimentina y focalmente para citoqueratina. Los hallazgos de la microscopia electrónica correspondieron a células mioepiteliales.
Asunto(s)
Humanos , Masculino , Femenino , Persona de Mediana Edad , Biopsia con Aguja , Neoplasias de las Glándulas Salivales , Mioepitelioma , Neoplasias de las Glándulas SalivalesRESUMEN
Colonic carcinomas with minimal or no glandular differentiation are a heterogeneous group of neoplasms which differ in their histologic appearance, clinical features, prognosis and molecular characteristics. Since 1990, we prospectively identified 11 patients with a predominantly solid (nonglandular) adenocarcinoma of the colon for which the term medullary adenocarcinoma of the colon (MAC) is proposed. The clinical, histological, histochemical, and immunohistochemical features of these neoplasms were studied. All patients with MAC were women with tumors in the cecum or proximal colon. Histological analysis showed nests or trabeculae of regular small to medium-sized cells with moderate amounts of eosinophilic cytoplasm; some cells contained mucin vacuoles. The nuclei had an open chromatin pattern and exhibited prominent nucleoli. Lymphatic permeation was present in most cases. Immunohistochemical reactions were positive for cytokeratin, carcinoembryonic antigen, and epithelial membrane antigen. Despite its histological resemblance with endocrine tumors, MAC is negative for endocrine markers. Of the eight patients for whom follow-up is available, four patients (two Dukes B and two Dukes C) are alive and well 1 to 4 years after surgery, one patient (Dukes C) died of tumor, one patient is alive with liver metastasis 4 years after surgery, and two patients died in the postoperative period. MAC appears to be a distinctive clinicopathologic entity. This tumor should be distinguished from other more aggressive, nonglandular tumors of the colon.
