Tumours of histiocytes and accessory dendritic cells: An immunohistochemical approach to classification from the International Lymphoma Study Group based on 61 cases

S. A. Pileri, T. M. Grogan, N. L. Harris, P. Banks, E. Campo, J. K C Chan, R. D. Favera, G. Delsol, C. De Wolf-Peeters, B. Falini, R. D. Gascoyne, P. Gaulard, K. C. Gatter, P. G. Isaacson, E. S. Jaffe, P. Kluin, D. M. Knowles, D. Y. Mason, S. Mori, H. K. Müller-HermelinkM. A. Piris, E. Ralfkiaer, H. Stein, I. J. Su, R. A. Warnke, L. M. Weiss

Research output: Contribution to journalArticlepeer-review

Abstract

Neoplasms of histiocytes and dendritic cells are rare, and their phenotypic and biological definition is incomplete. Seeking to identify antigens detectable in paraffin-embedded sections that might allow a more complete, rational immunophenotypic classification of histiocytic/dendritic cell neoplasms, the International Lymphoma Study Group (ILSG) stained 61 tumours of suspected histiocytic/dendritic cell type with a panel of 15 antibodies including those reactive with histiocytes (CD68, lysozyme (LYS)), Langerhans cells (CD1a), follicular dendritic cells (FDC: CD21, CD35) and S100 protein. This analysis revealed that 57 cases (93%) fit into four major immunophenotypic groups (one histiocytic and three dendritic cell types) utilizing six markers: CD68, LYS, CD1a, S100, CD21, and CD35. The four (7%) unclassified cases were further classifiable into the above four groups using additional morphological and ultrastructural features. The four groups then included: (i) histiocytic sarcoma (n = 18) with the following phenotype: CD68 (100%), LYS (94%), CD1a (0%), S100 (33%), CD21/35 (0%). The median age was 46 years. Presentation was predominantly extranodal (72%) with high mortality (58% dead of disease (DOD)). Three had systemic involvement consistent with 'malignant histiocytosis'; (ii) Langerhans cell tumour (LCT) (n = 26) which expressed: CD68 (96%), LYS (42%), CD1a (100%), S100 (100%), CD21/35 (0%). There were two morphological variants: cytologically typical (n = 17) designated LCT; and cytologically malignant (n = 9) designated Langerhans cell sarcoma (LCS). The LCS were often not easily recognized morphologically as LC-derived, but were diagnosed based on CD1a staining. LCT and LCS differed in median age (33 versus 41 years), male:female ratio (3.7:1 versus 1:2), and death rate (31% versus 50% DOD). Four LCT patients had systemic involvement typical of Letterer-Siwe disease; (iii) follicular dendritic cell tumour/sarcoma (FDCT) (n = 13) which expressed: CD68 (54%), LYS (8%), CD1a (0%), S100 (16%), FDC markers CD21/35 (100%), EMA (40%). These patients were adults (median age 65 years) with predominantly localized nodal disease (75%) and low mortality (9% DOD); (iv) interdigitating dendritic cell tumour/sarcoma (IDCT) (n = 4) which expressed: CD68 (50%), LYS (25%), CD1a (0%), S100 (100%), CD21/35 (0%). The patients were adults (median 71 years) with localized nodal disease (75%) without mortality (0% DOD). In conclusion, definitive immunophenotypic classification of histiocytic and accessory cell neoplasms into four categories was possible in 93% of the cases using six antigens detected in paraffin-embedded sections. Exceptional cases (7%) were resolvable when added morphological and ultrastructural features were considered. We propose a classification combining immuno-phenotype and morphology with five categories, including Langerhans cell sarcoma. This simplified scheme is practical for everyday diagnostic use and should provide a framework for additional investigation of these unusual neoplasms.

Original languageEnglish
Pages (from-to)1-29
Number of pages29
JournalHistopathology
Volume41
Issue number1
DOIs
Publication statusPublished - 2002

Keywords

  • Dendritic cell
  • Dendritic cell neoplasms
  • Follicular dendritic cell sarcoma
  • Histiocytic sarcoma
  • Interdigitating dendritic cell sarcoma
  • Langerhans cell tumour and sarcoma
  • Malignant histiocytosis
  • Mononuclear-phagocytic system
  • Reticuloendothelial system

ASJC Scopus subject areas

  • Anatomy
  • Pathology and Forensic Medicine
  • Cell Biology

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