Histopatholgical spectrum of thymic neoplasms: twelve-year experience at a referral hospital in north India.

This study was undertaken to determine the histopathological spectrum and clinical profile of thymic neoplasms at a tertiary referral care centre. A total of 96 thymectomy specimens were received during the study period (1992-2004), which consisted of 54 neoplasms and 42 benign lesions. Among the neoplasms there were 48 thymic epithelial tumors, 3 thymolipomas and 3 thymic carcinoids. The former comprised of 36 male (75%) and 12 female patients (25%) ranging in age from 2-70 years (mean 37 years). Among paraneoplastic syndromes in thymic epithelial tumours, 27 out of 48 (56.25%) cases were associated with myasthenia gravis and one case was associated with pure red cell aplasia. The most frequent histological subtype was cortical thymoma (43.24%) followed by predominantly cortical (24.32%) and well-differentiated thymic carcinoma (18.92%). On staging, all cases of mixed and predominantly cortical subtype were stage 1 whereas one medullary and 2 cortical thymomas and 4 well differentiated thymic carcinoma (WDTC) showed pleural and pericardial invasion (stage III). This study has revealed that half of thymic epithelial tumours presented as myasthenia gravis. The cortical thymoma was the most frequently encountered histologic subtype and most commonly associated with myasthenia gravis.

Clinicopathological study of thymomas--correlation of histologic subtype to myasthenia gravis and prognosis.

Thymoma is the most common primary tumor of anterior superior mediastinum. Sixty cases of thymomas over a 12 year period were analysed and the histologic subtype, according to Marino and Muller-Hermilink, classification was correlated with presence or absence of myasthenia gravis (MG) and capsular invasion. Thirty four patients had myasthenia gravis associated with thymoma and there was one case of pure red cell aplasia. There were 3 (1) predominantly cortical, 28 (20) cortical, 12 (9) mixed, 16 (4) medullary thymomas and 1 (0) thymic carcinoma (Figures in parenthesis indicate number of cases associated with MG). Capsular invasion was seen in 25 cases. Association with myasthenia gravis and capsular invasion were seen predominantly in cortical and mixed thymomas which were also associated with aggressive behaviour.

E-cadherin expression in thymomas

For the purpose of investigating the pattern of E-cadherin (E-CD) expression in thymomas, 72 cases were immunostained using monoclonal antibody (HECD-1) and microwave-enhanced immunohistochemical method on formalin-fixed, paraffin-embedded tissue sections. The thymomas were classified according to modified Muller-Hermelink classification. The spindle-shaped, medullary type tumor epithelial cells in medullary (3 cases) and composite type (20 cases) thymomas rarely expressed E-CD except in focal areas showing microcystic change observed in 8 cases. Meanwhile, the cohesive epithelioid tumor cells in every case of well-differentiated thymic carcinomas (WDTC) (29 cases) expressed E-CD. The epithelial cells in cortical type (13 cases) expressed stronger E-CD compared with those of organoid type (7 cases). In cases of WDTC admixed with cortical type, we observed increasing expression of E-CD as the tumor epithelium forms cohesive sheets. We could not find any loss of E-CD expression in invasive foci of the 11 cases of high-staged WDTC examined. Since the results of our study show a strong correlation between E-CD expression and epithelioid morphology of the tumor, E-CD seems to play a major role as a morpho-regulatory factor rather than as a suppressor of invasion in organotypic thymomas.

Tumores y quistes del mediastino / Mediastinum tumors and cysts

Los tumores y quistes del medistino son lesiones poco frecuentes, que se originan en las estructuras propias de cada uno de sus compartimientos o en elementos extramediastínicos que lo invaden. El logro de buenos resultados terapéuticos en este tipo de patología requiere de un diagnóstico preciso y oportuno lo cual no siempre es fácil. En este artículo se revisan algunos aspectos de estas lesiones, destacando sus relaciones anatómicas, presentación clínica y estudio de laboratorio. Se describen los tumores más frecuentes y sus respectivas características clínicas, los exámenes complementarios de mayor rendimiento y modalidades terapéuticas actualmente en uso

Timomas / Thymomas

Se analiza una serie integrada por 14 timomas, 6 benignos y 8 invasivos. La condición de malignidad se estableció por evidencia de propagación a la cápsula o a estructuras vecinas. En 3 pacientes se asocióa miastenia gravis, y sólo 1 de los restantes presentó síntomas respiratorios típicos. En los demás, fueron descubiertos por radiografías simples de tórax obtenidas por chequeo. Se ubicaron en los compartimientos previsceral y visceral medios, excepto uno, que se halló entre la columna y el hilio pulmonar. Un timoma calcificado pequeño carecía de traducción en la radiografía simple, aunque era evidente en la tomografía computada. Un timoma quístico de gran tamaño reemplaza gran parte de la imagen del pulmón. La aortografía fue útil para lesiones redondas en contacto con los grandes vasos, pero las tomografías lineales y la neumomediastinografía han sido ya reemplazados por la tomografía computada. Se extirpó el timoma en 9 pacientes con el seguimiento de 8. Los resultados de la cirugía fueron muy favorables, porque todos los controlados permanecen libres de enfermedad. Dos de los resecados con miastenia (un tercero fue inextirpable) experimentaron remisión del cuadro, parcial uno y completa el otro. La exéresis quirúrgica es la mejor terapéutica en casos operables, aún si de trata de tumores malignos, pudiéndose esperar resultados satisfactorios si la resección ha sido completa aunque haya debido ampliarse a órganos vecinos