title: Cystic well-differentiated squamous cell carcinoma of the thymus: a clinicopathological and immunohistochemical study of six cases.
abstract: OBJECTIVE
  To present six cases of cystic well-differentiated squamous cell carcinoma of the thymus.
  
  
  RESULTS
  The patients were six men aged between 48 and 75 years (average: 61.5 years) who were symptomatic with chest pain, shortness of breath, and dyspnoea. Diagnostic imaging showed anterior mediastinal masses, and surgical resection was accomplished in all cases. Grossly, the tumours measured 40-90 mm in greatest diameter (average: 65 mm), and were described as ill-defined lesions with a prominent cystic component and focal areas of haemorrhage and necrosis. Histologically, they were characterized predominantly by their cystic architecture. The cyst walls were lined by squamous epithelium showing different degrees of cellular atypia. In focal, more solid areas, the tumours showed evidence of keratinization. By immunohistochemistry, tumour cells were positive for cytokeratin 5/6, p40, and Pax8. All tumours were staged as T1N0M0 according to the Weissferdt-Moran staging system. Clinical follow-up showed that four patients have remained alive and well after a period ranging from 1 to 2 years. Two patients were lost to follow-up.
  
  
  CONCLUSIONS
  The current cases highlight an uncommon growth pattern of well-differentiated squamous cell carcinoma of the thymus that may cause diagnostic difficulty with mediastinoscopic biopsies.
authors.affiliation: Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Annikka
authors.initials: A
authors.lastname: Weissferdt
authors.affiliation: Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Neda
authors.initials: N
authors.lastname: Kalhor
authors.affiliation: Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Cesar A
authors.initials: CA
authors.lastname: Moran
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D003560:Cysts / Q000473:pathology; D004848:Epithelium / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D013953:Thymus Neoplasms / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor
keywords: cystic; mediastinum; squamous cell carcinoma; thymic carcinoma; thymus