Histopathologic changes of thymoma preoperatively treated with corticosteroids

Abstract

Preoperative treatment of thymoma in advanced stages with corticosteroids may reduce the size of the tumor, but no precise histologic evaluation has been performed. We examined the histopathologic features of pretreatment biopsy and posttreatment surgical specimens of eleven cases of thymoma with such treatment to see the changes of the histologic subtypes based on Muller-Hermelink classification. All specimens were also assessed immunohistochemically for MIB-1 labeling and apoptotic cells to verify the effectiveness of this pretreatment. Seven tumors clinically diminished in size after the treatment with corticosteroids. Fungal infection occurred in three cases postoperatively. The histology of mixed thymomas (two cases) was converted to that of medullary thymoma. Predominantly cortical thymomas (four cases) and cortical thymomas (three cases) changed to show similar histologic features; both became epithelial-rich thymoma with large polygonal tumor cells having indistinct cell borders. In contrast, two well-differentiated thymic carcinomas showed at surgery more prominent squamoid appearance with distinct cell borders. The apoptotic indices of epithelial cells were increased (P = 0.001), and the MIB-1 indices tended to be decreased with corticosteroid treatment. These results suggest that there may be a histogenetic relationship between medullary and mixed thymomas and also between predominantly cortical and cortical thymomas. Corticosteroids may cause degenerative changes in the epithelial cells and lymphocytes and, in thymomas in advanced stages, corticosteroid pretreatment may be warranted, although attention should be paid to infection after surgery.

Glucocorticoids induce G1 cell cycle arrest in human neoplastic thymic epithelial cells

“…Epithelial cell proliferation in thymoma may be regulated by other cellular components, such as thymocytes, macrophages, and dendritic cells (Masuda et al 1990). Thus, some degenerative changes in epithelial cells following glucocorticoid therapy may also be secondary to the depletion of thymocytes and the consequent defects in thymocyte-epithelial interactions (Tateyama et al 2001). To confirm the susceptibility of neoplastic TECs, we extended previous studies to tumor cells isolated from thymoma tissues in primary cultures.…”

“…Tateyama et al (Tateyama et al 2001) obtained similar results from TUNEL staining of sections, and suggested that glucocorticoids may have a suppressive A (a, b), AB (c, d), B1 (e, f), B2 (g, h), and B3 (i, j) thymoma tissues were stained with anti-GR (a, c, e, g, i), or anti-cytokeratin (b, d, f, h, j). GR expression was shown in both thymocytes and epithelial cells (·400) effect on the epithelial as well as the lymphocyte component of the tumor.…”

Thymic involution as a predictor of early-onset neonatal sepsis

“…22 Systemic LPS challenge results in a rise in plasma corticosterone levels and a pro-inflammatory cytokine cascade, which contribute to thymic involution via the preferential loss of thymocytes and characteristic remodelling of thymic stromal architecture. 23,24 The interplay between the supporting stromal environment and developing thymocytes has been well described and is considered to be crucial for robust thymopoiesis to occur. 25 Several studies using bone marrow chimeras have also speculated that leptin receptor expression on radioresistant thymus stroma may be important for thymic homeostasis during hypercorticosteronaemia.…”

Rapid regression of stage IVb invasive thymoma under palliative corticosteroid administration

“…Tateyama et al reported fungal infection as a side effect of steroids. 7 On the other hand, Funakoshi and colleagues described a potential mechanism of regression of thymomas by corticosteroids, indicating that neoplastic thymic epithelial cells express glucocorticoid receptors and that glucocorticoids directly induce G 1 cell cycle arrest and apoptosis. 8 Unfortunately, only 2 months after the regression our patient died of rapid progression of interstitial pneumonitis.…”

“…6 Tateyama et al reported that corticosteroid therapy may cause degenerative changes in some thymomas. 7 However, corticosteroid therapy, especially in high-dose or long-term therapy, should be considered cautiously because of various side effects. Tateyama et al reported fungal infection as a side effect of steroids.…”