RESUMO
Pituitary tumor initiation and progression are associated with a plethora of genetic imbalances. The role of pituitary trophic status as determinant of neoplastic potential is not clear. The pituitary gland responds to diverse central and peripheral signals by undergoing reversible plastic and functional changes. The resulting hyperplasia/excess hormone production, or involution/hyposecretion in pituitary cells may correlate with the ability to develop pituitary tumors. It is difficult to test this hypothesis, in part due to limitations on the definition of human pituitary cell trophic status and because this organ is not readily accessible for serial histopathological analysis. Therefore, animal models represent the most functional approach to testing this hypothesis. Transgenic mouse models of pituitary tumor transforming gene (PTTG) inactivation or overexpression support the notion that a permissive trophic environment may be required for pituitary tumor formation. Mechanisms underlying changes in pituitary plasticity and their relationship to tumor development may account for the diverse genetic abnormalities observed in pituitary tumors.
Assuntos
Adenoma/fisiopatologia , Neoplasias Hipofisárias/fisiopatologia , Adenoma/genética , Adenoma/patologia , Animais , Expressão Gênica , Humanos , Hipertrofia , Camundongos , Camundongos Transgênicos , Proteínas de Neoplasias/genética , Hipófise/patologia , Neoplasias Hipofisárias/genética , Neoplasias Hipofisárias/patologia , SecurinaRESUMO
OBJECTIVE: To describe a case of bilateral orbital lymphoma mistakenly diagnosed as Graves' ophthalmopathy. METHODS: We present a case report, with laboratory data and photographic documentation, and discuss the differential diagnosis in patients with orbital masses. RESULTS: A 65-year-old man with bilateral exophthalmos and substantial weight loss was referred to the Endocrine Clinic for evaluation of possible Graves' disease. A 6-cm mass was detected in the left axilla. Biopsy of this mass revealed the histopathologic diagnosis of anaplastic B-cell lymphoma. Treatment with intrathecally administered methotrexate and orally administered dexamethasone promptly resulted in decreased proptosis. CONCLUSION: The most frequent cause of bilateral proptosis is Graves' ophthalmopathy, and when it is associated with weight loss in an elderly patient, the initial diagnostic consideration is thyrotoxic Graves' disease. This case should remind physicians that bilateral orbital lymphoma, although uncommon, may mimic Graves' ophthalmopathy.
Assuntos
Doença de Graves/diagnóstico , Linfoma de Células B/diagnóstico , Neoplasias Orbitárias/diagnóstico , Idoso , Antimetabólitos Antineoplásicos/administração & dosagem , Antimetabólitos Antineoplásicos/uso terapêutico , Dexametasona/uso terapêutico , Diagnóstico Diferencial , Exoftalmia/etiologia , Glucocorticoides/uso terapêutico , Humanos , Injeções Espinhais , Linfoma de Células B/complicações , Linfoma de Células B/tratamento farmacológico , Masculino , Metotrexato/administração & dosagem , Metotrexato/uso terapêutico , Neoplasias Orbitárias/complicações , Neoplasias Orbitárias/tratamento farmacológico , Tomografia Computadorizada por Raios XRESUMO
We describe the case of a 41-year-old man with hoarseness and a hard, fixed mass in the anterior cervical region. He was referred to our endocrinology service for evaluation of possible thyroid cancer. The results of laboratory tests of thyroid function were normal. Indirect laryngoscopy revealed paralysis of the left hemilarynx and the presence of a large vegetating lesion. Computed tomography of the neck disclosed the presence of a mass in the anterior region, along with invasion and destruction of the adjacent structures. The cytologic diagnosis was established by analysis of a fine-needle aspiration biopsy specimen, which revealed a squamous cell carcinoma. The final diagnosis was carcinoma of the larynx.