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Systemic mast cell disease (mastocytosis). General aspects and histopathological diagnosis
H.-P. Horny, P. Ruck, S. Kröber and E. Kaiserling
Institute of Pathology, University of Tübingen, Tübingen, Germany
Offprint requests to: Prof. Dr. med. Hans-Peter Horny, Institut für Pathologie, Universität Tübingen , Liebermeisterstr. 8, 0-72076 Tübingen, Germany
Summary. Systemic mast cell disease/mastocytosis
(SMCD) is best defined as a multi topic proliferation of
cytologically and/or functionally abnormal tissue mast
cells (TMC). SMCD preferentially involves the bone
marrow, skin, spleen, liver, and lymph nodes. The
histopathological diagnosis of SMCD may be very
difficult to make, and the disease is often not considered
in the differential diagnosis of Iymphoreticular
neoplasia. In suspected cases of SMCD, basic dyes such
as Giemsa and toluidine blue are useful to demonstrate
the specific metachromatic granules of TMC. The
naphthol AS-D chloroacetate esterase reaction has also
proved to be very reliable for enzyme-histochemical
identification of TMC.
Major diagnostic problems may arise in cases of
malignant or «aggressive» SMCD exhibiting tissue
infiltrates consisting predominantly of highly atypical,
non-metachromatic TMC, which are usually also only
weakly reactive for chloroacetate esterase.
Immunostaining with antibodies against the mast
cell-specific proteases tryptase and chymase has proved
to be of great value for establishing the correct diagnosis
in such cases.
Anti-tryptase antibodies have major diagnostic
significance due to their extremely high sensitivity and
specificity. The classification of SMCD is controversial,
but there is increasing support for the differentiation of
at least two major subtypes that differ in prognosis: (i) a
benign or «indolent» variant in which skin involvement
(urticaria pigmentosa-like skin lesions) is usual, but
associated malignant hematological disorders are rare;
and (ii) a malignant or «aggressive» variant where skin
involvement is usually absent but concomitant malignant
hematological disorders (myelodysplastic and myeloproliferative
syndromes and acute non-lymphocytic
leukemias) are very common.
Preliminary molecular biological studies of a few
cases of malignant SMCD using the recently developed
HUMARA assay have yielded evidence that the disease
is monoclonal. Histol Histopathol 12, 1081-1089
(1997)
Key words: Malignant mastocytosis, Mast cell,
Mastocytosis, Systemic mast cell disease, Tryptase
DOI: 10.14670/HH-12.1081
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