[A Case of Essential Thrombocythemia with a JAK2V617F Mutation andPolymyalgia Rheumatica]

Area of Science:

• Rheumatology
• Hematology
• Genetics

Background:

• Polymyalgia rheumatica (PMR) is an inflammatory condition characterized by muscle pain and stiffness.
• Elevated inflammatory markers like C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and interleukin-6 (IL-6) are common in PMR.

Observation:

• A patient presented with PMR symptoms, elevated inflammatory markers, and significant thrombocytosis.
• The patient tested negative for rheumatoid factor (RF) and anti-cyclic citrullinated peptide (CCP) antibodies.
• Muscle pain improved with corticosteroid treatment.

Findings:

• Genetic analysis revealed a JAK2V617F mutation in the patient's peripheral white blood cells.
• Thrombocytosis was attributed to essential thrombocythemia (ET), a type of myeloproliferative neoplasm (MPN).
• The patient's muscle pain was considered secondary to ET with an inflammatory component.

Implications:

• This case underscores the necessity of considering myeloproliferative neoplasms, particularly ET, in the differential diagnosis of polymyalgia rheumatica, especially when thrombocytosis is present.
• The JAK2V617F mutation may play a role in the presentation of PMR-like symptoms.
• Early diagnosis and management of ET can potentially prevent severe complications such as cerebral infarction.