RESUMEN
OBJECTIVE: The aim of this study was to identify the prevalence of catecholamine excess and phaeochromocytomas in a well-defined population of people with hereditary head and neck paragangliomas. METHODS: We studied in a prospective follow-up protocol all consecutive patients referred to the Department of Endocrinology, Leiden University Medical Center, Leiden, The Netherlands with documented head and neck paragangliomas and either a positive family history for paragangliomas or a proven SDHD gene mutation. Initial analysis included medical history, physical examination and the measurement of excretion of catecholamines in two 24-h urine collections. In the case of documented catecholamine excess iodinated meta-iodobenzylguanidine (123I-MIBG) scintigraphy and magnetic resonance imaging were done. RESULTS: Between 1988 and 2003, 40 consecutive patients (20 male and 20 female) with documented head and neck paragangliomas were screened. Biochemical screening revealed urinary catecholamine excess in 15 patients (37.5%). In nine of these 15 patients a lesion was found by 123I-MIBG scintigraphy. Exact localization by magnetic resonance imaging revealed phaeochromocytomas in seven of the 15 patients. One of the nine patients had an extra-adrenal paraganglioma. Histopathological examination in a subset of tumors displayed loss of heterozygosity of the wild-type SDHD allele in all cases. CONCLUSIONS: The prevalence of catecholamine excess (37.5%) and phaeochromocytomas (20.0%) is high in patients with familial head and neck paragangliomas. Therefore, patients with hereditary head and neck paragangliomas require lifelong follow up by biochemical testing for catecholamine excess.
Asunto(s)
Neoplasias de las Glándulas Suprarrenales/orina , Catecolaminas/orina , Neoplasias de Cabeza y Cuello/orina , Proteínas de la Membrana/genética , Paraganglioma/orina , Feocromocitoma/orina , Neoplasias de las Glándulas Suprarrenales/genética , Neoplasias de las Glándulas Suprarrenales/metabolismo , Adulto , Estudios de Cohortes , ADN de Neoplasias/genética , Femenino , Mutación de Línea Germinal , Neoplasias de Cabeza y Cuello/genética , Humanos , Imidazoles , Pérdida de Heterocigocidad/genética , Masculino , Persona de Mediana Edad , Paraganglioma/genética , Feocromocitoma/genética , Estudios Prospectivos , Succinato DeshidrogenasaRESUMEN
Hereditary head and neck paragangliomas are tumours associated with the autonomic nervous system. Recently, mutations in genes coding for subunits of mitochondrial complex II, succinate-ubiquinone-oxidoreductase (SDHB, SDHC, and SDHD), have been identified in the majority of hereditary tumours and a number of isolated cases. In addition, a fourth locus, PGL2, has been mapped to chromosome 11q13 in an isolated family. In order to characterize phenotypic effects of these mutations, the present study investigated the immunohistochemical expression of the catalytic subunits of complex II (flavoprotein and iron protein), SDH enzyme activity, and mitochondrial morphology in a series of 22 head and neck paragangliomas. These included 11 SDHD-, one SDHB-, two PGL2-linked tumours, and eight sporadic tumours. In the majority of the tumours (approximately 90%), the enzyme-histochemical SDH reaction was negative and immunohistochemistry of catalytic subunits of complex II showed reduced expression of iron protein and enhanced expression of flavoprotein. Ultrastructural examination revealed elevated numbers of tightly packed mitochondria with abnormal morphology in SDHD-linked and sporadic tumours. Immuno-electron microscopy showed localization of the flavoprotein on the remnants of the mitochondrial inner membranes, whereas virtually no signal for the iron protein was detected. These results indicate that the function of mitochondrial complex II is compromised in the majority of head and neck paragangliomas.
Asunto(s)
Complejo II de Transporte de Electrones/genética , Neoplasias de Cabeza y Cuello/genética , Mitocondrias/patología , Paraganglioma/genética , Adulto , Anciano , Análisis Mutacional de ADN/métodos , ADN de Neoplasias/genética , Transporte de Electrón/genética , Flavoproteínas/análisis , Neoplasias de Cabeza y Cuello/enzimología , Neoplasias de Cabeza y Cuello/patología , Humanos , Inmunohistoquímica/métodos , Hierro/análisis , Proteínas Hierro-Azufre/genética , Proteínas de la Membrana/genética , Microscopía Electrónica/métodos , Persona de Mediana Edad , Proteínas de Neoplasias/genética , Paraganglioma/enzimología , Paraganglioma/patología , Subunidades de Proteína , Succinato Deshidrogenasa/genéticaRESUMEN
Recently, the Coverplate immunostaining method was introduced. This system allows easy handling of the slides and is suitable for immunoincubations for a variety of antigens at the same time on consecutive sections, without having to apply droplets of the individual primary antibodies on the sections. In this study, temperature rise inside the Coverplate units during microwave exposure is investigated. The most suitable conditions for microwave immunoincubations are determined. Immunoincubations with the Coverplate unit are conducted in the microwave oven and the results evaluated.