Timoma esclerosante: relato de caso / Sclerosing thymoma: case report

We present a rare case of thymoma in a 36-year old woman, who was initially diagnosed with severe myasthenia gravis and subsequently undergone surgical resection. During surgery tumor was found at the anterior mediastinum, tightly attached to the phrenic nerve, pleura and pericardium. Histological assessment showed large areas of sclerosis and fibrous collagenous tissue as well as islands of epithelial and lymphoid cells. Sclerosing thymoma, which is a rare subtype of thymoma (< 1%), was diagnosed, thus confirming the first report in Brazil. The patient showed partial improvement of symptoms associated with myasthenia gravis.

Relatamos um caso raro de timoma em uma mulher de 36 anos de idade, com clínica e diagnóstico de miastenia gravis de difícil controle clínico, submetida à ressecção cirúrgica. No intraoperatório, observou-se tumor no mediastino anterior, firmemente aderido ao nervo frênico, à pleura e ao pericárdio. Ao exame histológico, foram evidenciadas extensas áreas de tecido fibrocolagenoso e esclerose, assim como ilhas de células epiteliais e células linfoides. Diagnosticado timoma esclerosante, subtipo raro de timoma (< 1%), sendo este o primeiro caso relatado no Brasil. A paciente apresentou melhora parcial dos sintomas associados à miastenia 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.

[Thymoma: pathologic study]

The authors use the review of medical literature about thymoma - they report the classification system of Marino and Muller Hermelink. They fuis that there are correlation between this immunohistologic classification and morphologic thymoma. For prognosis we must study also macroscopic picture commun MASAOKA state

Estudio y seguimiento de 22 timomas linfoepiteliales del adulto / Study and follow-up of 22 lymphoepithelial thymonas in adults

Se presentan 22 casos de timonas linfoepiteliales del adulto, agrupados por estadios clínicos. Los 2 factores que determinaron la supervivencia fueron el carácter invasor y la miastemia gravis. Hubo 3 muertes postoperatorias en pacientes con miastenia gravis generalizada y timona maligno. Se hace hincapié en la importancia de la flebografía tímica y semiología angiológica del mediastino para el correcto tratamiento. La cirugía resectiva radical es el tratamiento de elección. La asociación de cobalto y quimioterapia es efectiva en estadios III y IV