Psoriasis and arthritis. III. A cross-sectional comparative study of patients with "psoriatic arthritis" and seronegative and seropositive polyarthritis: radiological and HLA aspects

MRI in psoriatic arthritis with hand and foot involvement

Evaluation of MRI-findings in patients with involvement of psoriatic arthritis (PsA) in small joints in hands and feet. Twenty-five patients with symptomatic joint involvement were studied by MRI. All patients were found to be positive for one or more imaging criteria. Soft tissue oedema was identified in 22/25 (88%) patients. Joint effusion was observed in 23/25 (92%) patients, whereas bone erosion was seen in 20/25 (80%) patients. Bone marrow oedema was evident in 21/25 (84%) cases. In 12/25 (48%) cases, bone proliferation was noted. Tendon sheath effusion was present in 17/25 (68%) patients. Contrast enhancement of the synovia was detected in all patients (n = 25) (100%), whereas adjacent periost was enhanced in 22/25 (88%) and epiphysial bone marrow in 18/25 (72%) patients. MRI allows the assessment of PsA-alterations of soft tissue, cartilage, bone, bone marrow, and adjacent tendon sheath in patients with hand and foot involvement.

Psoriatic arthritis

Despite the fact that psoriatic arthritis has been recognized as an entity for almost five decades, there are still no valid criteria for either its diagnosis or classification. Several sets of criteria have been proposed but none was studied. None the less, investigators have been able to study the condition and describe its unique features and its natural course and prognosis. However, in order to facilitate further studies, it would be worthwhile to develop an internationally accepted and validated set of criteria, both for the diagnosis and classification of the disease, as well as for the assessment of damage. These criteria would help set up appropriate therapeutic trials in this condition as well.

Psoriatic arthritis. Historical background and epidemiology

Psoriatic arthritis was first described in the early part of the nineteenth century. Over the past 50 years, concepts of the disease have evolved as a result of clinical, epidemiological, radiological and immunogenetic study. Epidemiological and clinical investigations suggest that the disease is a unique arthropathy rather than the coincident occurrence of two common diseases. There are no validated criteria for classification; this is partly because of the heterogeneous clinical features associated with the disease, and the relapsing and remitting nature of both psoriasis and arthritis. Clinical subgroups have been proposed and have proved useful in study of the disease; however, there are inconsistencies and overlaps in the published data. The population prevalence of psoriatic arthritis is in the range of 2-10 per 10,000 although this is probably an underestimate as those with sacroiliac involvement only are not included. There are currently no incidence figures from population samples. The disease is slightly more common in females than males, although there is variation in the sex ratio by disease subgroup. There is evidence that hormonal and environmental factors play a role in the occurrence of disease.

Psoriatic arthritis. Genetics and HLA antigens

There is convincing evidence of a genetic basis for both psoriasis and psoriatic arthritis (PsA). Part of this genetic predisposition is due to genes within the major histocompatibility complex (MHC). In psoriasis, the primary association is with HLA-Cw6. Further work on specific nucleotide frequencies, especially those in the alpha 1 domain helix of the HLA-C molecule, will be of interest in determining whether a specific nucleotide frequency is present in all patients. The situation in PsA is considerably more complex. It is now established that there is an association between HLA-B27 and PsA, both in its peripheral arthropathy and in spinal disease in which radiological sacroiliitis is present. Spinal disease without radiological sacroiliitis is probably not associated with HLA-B27. There is some suggestion that HLA-B16 or its splits, HLA-B38 and HLA-B39, may also be associated with PsA, but there is considerable heterogeneity between the series, which prevents a firm conclusion being made. It is possible, but again not conclusive, that there is an association between HLA-DR4 and the symmetrical seronegative pattern of peripheral PsA. It is also likely that genes outwith the MHC predispose to psoriasis and PsA. It is further likely that a role will be found for environmental factors in both psoriasis and PsA. There is a tantalizing possibility of a complex interplay between a variety of environmental factors and genetic factors, both within and outwith the MHC, determining not only susceptibility but also the individual clinical pattern of disease. Further clarification of these possibilities is likely to depend primarily on understanding the role of genes within the MHC in predisposing to comparatively more homogeneous diseases, such as psoriasis and ankylosing spondylitis, before the mechanisms operating in PsA can be analysed and better understood.

Natural history of psoriatic arthritis

Psoriatic arthritis is a distinct form of inflammatory arthritis associated with psoriasis, which exists in a number of clinical presentations. Although a large number of patients have a mild form of arthritis, there is a population who present with a very aggressive, deforming and disabling arthritis. The prognostic factors for the development of this type of arthritis are unclear as yet. Therefore, PsA may not be as benign a condition as previously thought, and the approach to its management should be similar to that for rheumatoid arthritis. Current investigations are in progress to identify the prognostic factors associated with severe disease in PsA. Until the results of these studies are available, all patients should probably be treated more aggressively, and earlier.

Technetium-99m human immunoglobulin scintigraphy in psoriatic arthropathy: first results

Standard bone scintigraphy [using technetium-99m methylene diphosphonate (MDP)] is widely held to be the most sensitive method for the early detection of psoriatic arthropathy. Preliminary results of this study reveal that 99mTc human immunoglobulin (HIG) scintigraphy demonstrates a typical premature pattern of extradermal psoriatic disease in digits indicative of the early stage of psoriatic arthritis. This pattern was also found in a rare case of psoriatic arthropathy without skin lesions. 99mTc-HIG scintigraphy appears to reveal the initial inflammatory characteristics of later bone lesions. In the advanced stage of psoriatic arthritis, 99mTc-MDP and 99mTc-HIG scans were found to be equally sensitive in the detection of the affected joints. Thus 99mTc-HIG scintigraphy seems to be useful in the early detection of psoriatic arthropathy and also in advanced psoriatic arthritis, as well as for the detection of psoriatic arthropathy without skin lesions.

Isolated lesions of the manubriosternal joint in patients with inflammatory back pain and negative sacroiliac and spinal radiographs

The prevalence of radiological lesions of the manubriosternal joint was assessed in 151 patients with chronic inflammatory back pain and in 31 controls with non-inflammatory back pain. Nineteen out of these 151 patients and none of the controls showed unequivocal lesions of the manubriosternal joint without accompanying radiological lesions of the sacroiliac joints or the lumbar spine. Thoracic pain and stiffness were present in 7 out of the 19 patients and in 3 out of the 31 controls (P less than 0.05); peripheral enthesopathy was present in 10 out of the 19 patients and in 4 out of the 31 controls (P less than 0.01); none of the patients or controls had rheumatoid factor, subcutaneous nodules, or peripheral arthritis. The suggestion of a "manubriosternal joint syndrome" is warranted by these findings.

Psoriasis and arthritis. II. A cross-sectional comparative study of patients with "psoriatic arthritis" and seronegative and seropositive polyarthritis: clinical aspects

Arthritis of the terminal joints of the hands and feet occurred more frequently (P less than 0.015) in patients with seronegative poly-arthritis combined with psoriasis (S- P+; n = 92) than in patients with seronegative polyarthritis alone (S- P-; n = 72). However, the prevalence of affection of these joints was too low to consider this feature a sensitive marker for psoriatic arthritis. Furthermore, neither asymmetrical joint involvement nor the absence of ulnar deviation of the fingers appeared to be characteristic of this disease. A positive correlation was found between the presence of nail psoriasis and limitation of function of the distal interphalangeal (DIP) joints. The DIP finger joints and the interphalangeal joints of the toes were affected more often in the S- P+ group than in patients with seropositive polyarthritis without psoriasis (S+ P-; n = 46), but arthritis of the other joints was observed more frequently in the latter group.