THE VALUE OF IMMUNOHISTOCHEMISTRY
IN THE ASSESSMENT OF BONE MARROW DISORDERS
Attilio Orazi, M.D., FRCPath. and Dennis P. O'Malley, M.D.
CD1A and S-100
CD1a is the most specific marker for Langerhans cells (LC) and LC histiocytosis that is currently available.
The mouse monoclonal O10 antibody which reacts well with conventionally processed bone marrow biopsy can be
used to demonstrate LC in bone marrow biopsies. In addition, since CD1a is also expressed in cases of
precursor T- cell acute lymphoblastic leukemia/lymphoblastic lymphoma, the antibody can be used to
immunophenotype such cases. S-100 although less specific than CD1a can be useful to confirm a diagnosis of
LCH. S-100 also stains cases of malignant histiocytosis (CD68 positive, CD1a negative), histiocytes in
Rosai-Dorfman disease, NK lymphocytes, and among many solid neoplasms, in particular, cases of malignant
melanoma and schwannoma.
- Emile et al: Langerhans' cell histiocytosis. Definitive diagnosis with the use of monoclonal antibody
O10 on routinely paraffin-embedded samples. Am J Surg Pathol. 1995;19:636-41.
- Pileri et al: Acute leukaemia immunophenotyping in bone-marrow routine sections. Br J Haematol.