title: Angiomatoid neuroendocrine carcinoma of the thymus: report of a distinctive morphological variant of neuroendocrine tumor of the thymus resembling a vascular neoplasm.
abstract: Three cases of primary thymic neuroendocrine tumors characterized by prominent angiomatoid features that resembled a vascular neoplasm are presented. The patients were all men between 52 and 59 years of age who presented with chest pain and shortness of breath attributable to a large anterior mediastinal mass. The lesions ranged in size from 6 cm to 15 cm in greatest diameter, and were grossly soft and well circumscribed, but not encapsulated. The cut surface was remarkable for multiple blood-filled cyst-like spaces admixed with focal solid, hemorrhagic areas. Histologically, the tumors contained multiple cystically dilated spaces filled with blood which imparted the lesion with a striking angiomatoid appearance. The walls of the cysts were lined by a monotonous proliferation of round to oval cells with distinct cell borders, round central nuclei, and abundant eosinophilic cytoplasm. Mitotic activity was present in all cases and varied from 3 to 8 mitoses per 10 high-power fields. Immunohistochemical studies performed in two cases showed positivity of the tumor cells for keratin, Leu 7, and synaptophysin, and focal chromogranin positivity in one. Follow-up information obtained in two patients showed that both had died of tumor 4 and 8 years after initial diagnosis. The present cases show an unusual morphological appearance of thymic neuroendocrine tumors that may be mistaken for a vascular neoplasm. Immunohistochemical stains may be of importance in such instances in arriving at the correct diagnosis.
authors.affiliation: Department of Pulmonary and Mediastinal Pathology, Armed Forces Institute of Pathology, Washington, DC, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Moran
authors.forename: S
authors.initials: S
authors.lastname: Suster
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism; D002276:Carcinoid Tumor / Q000378:metabolism / Q000473:pathology*; D018278:Carcinoma, Neuroendocrine / Q000378:metabolism / Q000473:pathology*; D003937:Diagnosis, Differential; D017809:Fatal Outcome; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D013953:Thymus Neoplasms / Q000378:metabolism / Q000473:pathology*; D019043:Vascular Neoplasms / Q000378:metabolism / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor