Ectopic hamartomatous thymoma: a case report showing CD99+ lymphocytes and a low proliferation index

Arch Pathol Lab Med. 2003 Sep;127(9):e378-81. doi: 10.5858/2003-127-e378-EHTACR.

Abstract

Ectopic hamartomatous thymoma is a rare benign tumor that consists of spindle, epithelial, and adipose cell elements. We present a case of this lesion arising in the supraclavicular region of a 59-year-old man, including the characteristic immunohistochemical and ultrastructural findings. DNA flow cytometry revealed diploidy with a low proliferation index (6.73%). The tumor contained CD99+ lymphocytes; CD99 (MIC2) can serve as a useful marker of immature T cells. These findings suggest that ectopic hamartomatous thymoma may develop from the third branchial pouch or thymic anlage.

Publication types

  • Case Reports

MeSH terms

  • 12E7 Antigen
  • Antigens, CD / analysis
  • Antigens, CD34 / analysis
  • CD3 Complex / analysis
  • Cell Adhesion Molecules / analysis
  • Cell Division
  • Choristoma / metabolism
  • Choristoma / pathology*
  • Hamartoma / metabolism
  • Hamartoma / pathology*
  • Hamartoma / ultrastructure
  • Humans
  • Immunohistochemistry
  • Keratins / analysis
  • Leukocyte Common Antigens / analysis
  • Lymphocytes / chemistry
  • Lymphocytes / pathology
  • Male
  • Microscopy, Electron
  • Middle Aged
  • Mitotic Index
  • Mucin-1 / analysis
  • Thymoma / metabolism
  • Thymoma / pathology*
  • Thymoma / ultrastructure
  • Thymus Neoplasms / metabolism
  • Thymus Neoplasms / pathology*
  • Thymus Neoplasms / ultrastructure

Substances

  • 12E7 Antigen
  • Antigens, CD
  • Antigens, CD34
  • CD3 Complex
  • CD99 protein, human
  • Cell Adhesion Molecules
  • Mucin-1
  • Keratins
  • Leukocyte Common Antigens