Myeloproliferative neoplasms
The classification of these conditions is based on WHO criteria.
This group includes polycythaemia vera (Polycythaemia Vera), the main feature of which is erythrocytosis. Diagnosis requires meeting three major criteria (hemoglobin >16.5 g/dL in men or >16.0 in women, panmyelosis on bone marrow biopsy with pleomorphic megakaryocytes, and presence of the JAK2 V617F or exon 12 mutation) OR two major criteria plus one minor criterion (decreased erythropoietin levels). The disease most commonly affects women aged 50–55 years, presenting with thrombosis, pruritus, plethora, and splenomegaly. Median survival reaches 14 years. Treatment includes regular phlebotomy to maintain hematocrit below 45% and low-dose aspirin.
Another condition is primary myelofibrosis (Primary Myelofibrosis). In this disorder, clonal cell proliferation leads to progressive replacement of the bone marrow by fibrous tissue. This causes fatigue, dyspnea, weight loss, pancytopenia, and prompts the body to initiate extramedullary hematopoiesis. Hematopoietic foci most commonly develop in the spleen (splenomegaly in 94% of cases) and liver (72%), but may also affect lymph nodes, lungs, and even the choroid plexus. Myelofibrosis can also be secondary, occurring as a late complication of polycythaemia vera.
Plasma cell dyscrasias
Multiple myeloma (Multiple Myeloma) is diagnosed in the presence of associated end-organ damage, including hypercalcemia, renal impairment, anemia, bone lesions, and amyloidosis. It is crucial to identify patients with asymptomatic, "smoldering" myeloma—they must undergo osteoporosis screening via dual-energy X-ray absorptiometry (DEXA), as their fracture risk is significantly increased.
A distinct entity is solitary bone plasmacytoma (Solitary Plasmacytoma of Bone). It manifests earlier than multiple myeloma, is more common in men, and predominantly affects the axial skeleton (vertebrae, pelvis, ribs). Patients typically present with bone pain or a pathological fracture. Median survival is approximately 10 years.
Radiological diagnosis of lesions
Radiological methods play a pivotal role in assessing disease extent.
- Polycythaemia vera: MRI reveals diffuse signal drop on T1-weighted scans and hyperintensity on STIR imaging, reflecting bone marrow hyperplasia. Progression to acute myeloid leukemia may be occult on imaging unless myeloid sarcoma is present.
- Multiple myeloma: The diagnostic workup standard includes whole-body low-dose CT, MRI, or PET/CT. Detection of more than one focal lesion on MRI is an absolute indication for initiating therapy.
- Solitary plasmacytoma: The tumor grows from the medullary cavity. On radiographs or CT, it appears as a lytic, destructive lesion with well-defined margins causing cortical thinning. A characteristic pattern—visible trabeculation creating a "soap bubble" appearance—is often observed.
- Primary bone lymphoma: Unlike plasmacytoma, it presents with a "moth-eaten" destruction pattern (moth-eaten) with low-signal bone marrow replacement on T2-weighted MRI and frequent involvement of regional lymph nodes.
Briefly: answers to topical questions
Which genetic mutations and with what frequency are detected in primary myelofibrosis?
Primary myelofibrosis (Primary Myelofibrosis) is characterized by the JAK2 mutation, which occurs in 55% of cases. The presence of this genetic anomaly confirms the diagnosis. Primary myelofibrosis is a myeloproliferative neoplasm of unknown etiology, in which clonal proliferation of hematopoietic stem cells leads to progressive bone marrow fibrosis.
What are the incidence rates and median survival for polycythaemia vera?
Epidemiological and prognostic indicators for polycythaemia vera (Polycythaemia Vera) include the following data:
- Incidence — 1.5–2.0 per 100,000 population.
- Median survival — approximately 14 years.
The average age at onset is 50–55 years, with a 2-fold higher prevalence in women.
POEMS is an acronym for a rare syndrome seen in plasma cell dyscrasias: Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal Ig, Skin changes.
Class and exam questions
What diagnostic criteria are required to diagnose polycythaemia vera?
Requires three major criteria (elevated hemoglobin, hypercellular bone marrow on biopsy, JAK2 mutation) OR two major and one minor criterion (decreased serum erythropoietin levels).
What does a solitary plasmacytoma look like on radiographs?
This is a lytic destructive lesion within the medullary canal with relatively slow growth. It frequently causes bone expansion and cortical thinning with the formation of a "soap bubble" appearance.
What is extramedullary hematopoiesis and where does it most commonly occur?
This refers to the formation of hematopoietic foci outside the bone marrow, characteristic of myelofibrosis; the spleen (in 94% of cases) and liver (in 72% of cases) are most frequently involved.
What else to study on this topic
- Cytoreductive therapy and management of high-risk patients in polycythaemia vera
- Differential diagnosis of primary and secondary myelofibrosis
- MGUS criteria and monitoring algorithm for patients with smoldering myeloma
- Specifics of PET/CT and whole-body MRI protocols in multiple myeloma
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