Axial spondyloarthritis (including ankylosing spondylitis) – this involves the spine, although an RA-like symmetrical small-joint polyarthritis may occur in the context of this condition. Hepatitis C – RA-like symmetrical small-joint polyarthritis may occur in the context of this condition. Hepatitis C may also induce rheumatoid factor auto-antibodies.Rarer causes which usually behave differently but may cause joint pains:
Sarcoidosis, amyloidosis, and Whipples disease can also resemble RA. Hemochromatosis may cause hand joint arthritis. Acute rheumatic fever can be differentiated by a migratory pattern of joint involvement and evidence of antecedent streptococcal infection. Bacterial arthritis (such as by Streptococcus) is usually asymmetric, while RA usually involves both sides of the body symmetrically. Gonococcal arthritis (a bacterial arthritis) is also initially migratory and can involve tendons around the wrists and ankles.Sometimes arthritis is in an undifferentiated stage (i.e. none of the above criteria is positive), even if synovitis is witnessed and assessed with ultrasound imaging. Difficult-to-treat
Rheumatoid arthritis (D2T RA) is a specific classification RA by the European League against Rheumatism (EULAR).Signs of illness:

Persistence of signs and symptoms
Drug resistance
Does not respond on two or more biological treatments
Does not respond on anti-rheumatic drugs with different mechanism of actionFactors contributing to difficult-to-treat disease:

Genetic risk factors
Environmental factors (diet, smoking, physical activity)
Overweight and obese

Genetic factors
Genetic factors such as HLA-DR1B1, TRAF1, PSORS1C1 and microRNA 146a are associated with difficult to treat rheumatoid arthritis, other gene polymorphisms seem to be correlated with response to biologic modifying anti-rheumatic drugs (bDMARDs). Next one is FOXO3A gene region been reported as associated with worst disorder.
Fibrolamellar hepatocellular carcinoma (FHCC) is a rare form of hepatocellular carcinoma (HCC) that typically affects young adults and is characterized, under the microscope, by laminated fibrous layers interspersed between the tumour cells. Approximately 200 new cases are diagnosed worldwide each year. Cause
A recent study showed the presence of the DNAJB1-PRKACA chimeric transcript (resulting from a 400kb somatic deletion on chromosome 19) in 100% of the FHCCs examined (15/15) This gene fusion has been confirmed in a second study. Pathology
The histopathology of FHCC is characterized by laminated fibrous layers, interspersed between the tumor cells. Cytologically, the tumor cells have a low nuclear to cytoplasmic ratio with abundant eosinophilic cytoplasm. Tumors are non-encapsulated, but well circumscribed, when compared to conventional HCC (which typically has an invasive border). Diagnosis
Due to lack of symptoms, until the tumor is sizable, this form of cancer is often advanced when diagnosed. Symptoms include vague abdominal pain, nausea, abdominal fullness, malaise and weight loss. They may also include a palpable liver mass. Other presentations include jaundice, ascites, fulminant liver failure, encephalopathy, gynecomastia (males only), thrombophlebitis of the lower limbs, recurrent deep vein thrombosis, anemia and hypoglycemia.The usual markers for liver disease – aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase – are often normal or only slightly elevated. FHCC often does not produce alpha fetoprotein (AFP), a widely used marker for conventional hepatocellular carcinoma.