Table 3.
Main non-infectious etiologies for refractory mono- or poly-arthritis: WHAT do you find?
| Disease | Histology |
|---|---|
| Ochronosis (43) | Paraffin-embedded sections show yellow-brown shards (able to provoke foreign body reactions with histiocytes and giants cells), scattered over the synovium and brittle pigmented articular cartilage. Haemosiderin and ochronotic pigment in macrophages, and focal inflammatory infiltrate of lymphocytes and plasma cells with some lining layer hyperplasia and hypervascularity may also be seen. |
| Hemochromatosis (44) | Low degree of synovial hyperplasia with mild infiltration of neutrophils, mononuclear cells -comprising macrophages- and lymphocytes; formation of synovial microvessels; haemosiderin deposition in the synovial lining cells; CPPD crystals may be seen. |
| Amyloidosis (45) | Diagnosis of amyloidosis requires Congo red staining to show amyloid deposits in the synovium. The immunohistochemical study allows typing of amyloidosis: antibodies directed against light chains of immunoglobulins (AL-amyloidosis), antibodies against the other major amyloid proteins (AA and ATTR). |
| Multicentric reticulohistiocytosis (46, 47) | Lipid-laden multinucleated giant cells and histiocytes with ground glass PAS-positive cytoplasm, which contains membrane-bound lysosomal granules, with a single large stellate Golgi apparatus. |
| Sarcoidosis (48, 49) | Histopathological examination of synovium reveals various patterns: diffuse infiltration with histiocytes and lymphocytes, mild lining cell proliferation, seldom vascular congestion. A granulomatous reaction is often absent. |
| Crystal arthropathies (50) | Gout and pseudogout: deposits of monosodium urate crystals or calcium pyrophosphate dihydrate crystals in the synovium after fixation with absolute alcohol and analysis with a polarization microscope, which shows to evaluate birefringence properties (negative MSU, positive CPPD), or DeGolanthal staining method. Basic calcium phosphate induced arthritis: crystals can be seen using alizarin red staining or transmission or scanning electron microscopy. |