Felsopathoidit

Felsopathoidit is a rare inflammatory syndrome described in a limited number of case reports and reviews. It is defined by chronic musculoskeletal pain, episodic fever or malaise, and the development of periarticular or soft tissue calcifications that resemble stone-like nodules.

Clinical features include migratory or fluctuating joint pain, morning stiffness, swelling of affected joints, and fatigue. In some cases, palpable subcutaneous nodules or calcified deposits are observed in periarticular tissues. Laboratory findings often show elevated inflammatory markers (CRP, ESR) during flares, with nonspecific autoimmune serology.

Etiology remains unclear. Most reported cases suggest non-infectious, autoinflammatory or autoimmune mechanisms. No single genetic or environmental factor has been established. Associations with metabolic disorders affecting calcium/phosphate balance have been proposed but are not consistently observed.

Diagnosis is by clinical assessment supported by imaging and exclusion of infection or crystal arthropathies. Imaging (X-ray, ultrasound, CT) may reveal periarticular calcifications, soft tissue nodules, and occasionally joint erosion. Biopsy can show granulomatous or inflammatory tissue with calcifications but is not routinely required.

Management focuses on symptom control and preventing flares. Nonsteroidal anti-inflammatory drugs and, when needed, corticosteroids are used for pain and inflammation. Disease-modifying antirheumatic drugs or biologic agents may be considered in persistent cases. Physical therapy and lifestyle measures assist function; surgical removal of problematic calcifications is occasionally performed.

Felsopathoidit is exceedingly rare, with most knowledge derived from isolated reports. No established prevalence, risk factors, or standardized diagnostic criteria exist. Further study is needed to determine its natural history and optimal management.