Spindle Cell Thymomas (WHO Type A) With Prominent Papillary and Pseudopapillary Features

Department of Pathology, University of Texas, MD Anderson Cancer Center, Houston, USA.
The American journal of surgical pathology (Impact Factor: 5.15). 03/2011; 35(3):372-7. DOI: 10.1097/PAS.0b013e318208354b
Source: PubMed


Ten cases of spindle cell thymomas with prominent papillary and pseudopapillary features were presented. The patients were 7 men and 3 women between the ages of 47 and 75 years. Clinically, 3 patients were asymptomatic, 1 patient presented with chest pain, 4 patients with shortness of breath, and 1 patient with a history of pulmonary tuberculosis. One case was found during an autopsy procedure. Nine patients underwent complete surgical resection of their mediastinal tumors, which varied in size from 4 to 9 cm in greatest diameter. Histologically, all tumors showed a spindle cell appearance (WHO type A) with elongated nuclei and inconspicuous nucleoli. Scattered lymphocytes were present admixed with the spindle cellular proliferation. In addition, all tumors showed prominent areas of papillary and pseudopapillary features, which varied in size and type. In some cases, prominent areas of hyalinization were also present, whereas in other cases the papillary-like changes were composed of edematous projections, which imparted these tumors a unique morphologic growth pattern. Three tumors were encapsulated, whereas 7 other tumors were invasive. Immunohistochemical studies for keratin CAM5.2 and keratin 5/6 showed strong positive reaction, whereas other stains including CEA, calretinin, CD-31, and thyroglobulin were negative. Follow-up information showed that 2 patients are alive and well, whereas 3 patients have died. No follow-up information was obtained in 4 patients. The current morphologic appearance has not been previously emphasized in thymomas, which is important to recognize to avoid misdiagnosis with other mediastinal neoplasms.

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    ABSTRACT: Ten cases of an unusual growth pattern of thymomas are presented. The patients were 8 men and 2 women between the ages of 43 and 62 years. Clinically, 6 patients presented with symptoms of chest pain, cough, and shortness of breath, whereas 4 patients were asymptomatic. Surgical resection of the mediastinal mass was performed in all patients obtaining tumors that varied in size from 4 to 11 cm in greatest dimension. Grossly, the tumors were described as round and well defined, which, at cut surface, showed a firm consistency with a slight lobulated appearance. Areas of necrosis and/or hemorrhage were not present. Histologically, all the tumors showed similar growth pattern characterized by the presence of cells arranged in small cords dissecting fibroconnective tissue and, in some areas, resembling "signet ring" cells. Mitotic activity was not present. Using the Masaoka staging system, 6 cases were in stage I, and 4 cases were in stage II. Histochemical stains for periodic-acid Schiff stain with diastase and mucicarmine were negative for intracytoplasmic mucin. Immunohistochemical studies for CAM5.2 and cytokeratin 5/6 showed a strong positive reaction, whereas thyroid transcription factor 1, epithelial membrane antigen, calretinin, α-fetoprotein, and CD31 were all negative. Follow-up information obtained for 7 patients between 1 and 12 years showed that all these patients are alive and well. The current cases highlight an unusual histologic growth pattern of thymomas that likely can be confused with other tumors of the anterior mediastinum that may require different treatment approaches and carry a different prognosis.
    No preview · Article · May 2012 · Human pathology
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    ABSTRACT: Spindle cell thymomas are a subset of thymoma that is characterized by great morphologic variability. This histologic complexity coupled with the overall rarity of these lesions can easily cause diagnostic confusion with other spindle cell neoplasms of the anterior mediastinum. In this review, we summarize the various morphologic patterns that have been described in the peer-reviewed literature and present additional patterns that we have encountered in our practice. Familiarity with the histomorphologic spectrum of spindle cell thymomas is essential to diagnose these tumors correctly and distinguish them from other mediastinal spindle cell lesions that require different treatment modalities.
    No preview · Article · Dec 2012 · Human pathology
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    ABSTRACT: Twelve cases of thymomas with prominent glandular differentiation are presented. The patients were 7 men and 5 women aged between 45 and 68 years (average, 56.5 years). Clinically, the patients presented with nonspecific symptoms of chest pain, cough, and fatigue. None of the patients had a history of myasthenia gravis or other autoimmune syndrome. Thymectomy was performed in all patients. The tumor size ranged from 4 to 7 cm in greatest diameter. Macroscopically, the tumors were described as firm and light tan without areas of necrosis, hemorrhage, or cystic change. Histologically, 7 tumors were classified as spindle cell (World Health Organization type A), 2 as mixed spindle cell and conventional (A+B1), 2 as conventional (B1), and 1 as atypical thymoma (B3). In 4 cases, the tumors showed invasion into periadipose thymic tissue. All cases showed the typical growth patterns of their particular subtypes. In addition, a distinct glandular component was present in all cases showing mucinous differentiation in 4 of them. Immunohistochemical studies showed tumor cells positive for CAM5.2, cytokeratin 5/6, and Pax8 and negative for carcinoembryonic antigen, thyroid transcription factor 1, and epithelial membrane antigen. Calretinin showed focal weak staining in the nonmucinous glandular components in 3 cases. Follow-up information obtained in 8 patients showed that all were alive and well in a period ranging from 2 to 5 years. The possibility of a glandular component in thymomas should be kept in mind in the assessment of mediastinoscopic biopsies to avoid misdiagnosis for other neoplasms that may require different treatment modalities.
    No preview · Article · Mar 2013 · Human pathology
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