Diagnostic markers
To confirm the diagnosis, physicians use a set of laboratory, immunological, and cytogenetic criteria:
- Cytogenetics: detection of the characteristic point mutation in codon 816 of the C-Kit gene, which encodes the growth factor receptor CD 117-Kit.
- Immunophenotype: determination of the co-expression of cellular markers CD2 and/or CD25.
- Laboratory parameters: significant increase in serum total tryptase levels in the patient.
Classification of mast cell neoplasms
According to the World Health Organization (WHO) classification, the pathology is divided into several main forms and variants:
- Cutaneous mastocytosis — the pathological process is localized predominantly in the skin.
- Indolent systemic mastocytosis — may occur with or without skin involvement, with a bone marrow infiltration degree of less than 30%.
- Systemic mastocytosis associated with clonal hematological non-mast cell lineage disease — may also be accompanied by skin involvement in the pathological process.
- Aggressive systemic mastocytosis — characterized by multiorgan infiltration, clonal proliferation of atypical mast cells, and less than 20% immature forms in the bone marrow.
- Mast cell leukemia/sarcoma — a severe form in which more than 20% immature mast cells are detected in the bone marrow.
Localization of the pathological process
The increase in the number of mast cells in this condition is not limited to a single anatomical zone. Pathological infiltration may encompass:
- Skin
- Bone marrow
- Liver and spleen tissues
- Gastrointestinal tract
- Other organs in systemic and aggressive forms of the disease
Briefly: answers to topical questions
What clonal hematological disorders are most commonly associated with systemic mastocytosis?
Systemic mastocytosis can be associated with hematological neoplasms. Associated conditions include:
- Myelodysplastic syndromes (MDS).
- Myeloproliferative neoplasms.
- Leukemias.
- Lymphomas.
The WHO classification distinguishes a subgroup: systemic mastocytosis with an associated hematological neoplasm (SM-AHN).
C-Kit cells increase tryptase in the skin and bone marrow.
Class and exam questions
What changes occur in the body during mastocytosis?
The primary manifestation of the disease is a significant increase in the number of mast cells in various body tissues, including the skin, bone marrow, spleen, liver, and gastrointestinal tract.
What genetic defect is characteristic of this condition?
The main cytogenetic marker is a point mutation in codon 816 of the C-Kit gene, which is responsible for the CD 117-Kit growth factor receptor.
How are forms with bone marrow involvement classified by degree of infiltration?
In the indolent form, infiltration is less than 30%; in the aggressive form, it is less than 20% immature mast cells with signs of clonal proliferation; and in mast cell leukemia, it is more than 20% immature forms.
What else to study on this topic
- WHO diagnostic criteria for systemic mastocytosis
- Features of clinical manifestations of cutaneous mastocytosis
- Differential diagnosis of aggressive forms and leukemia
- The role of tryptase in symptom pathogenesis
- Morphological picture of bone marrow biopsies
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