Complications of psoriasis

Place in the Spondyloarthropathy Group

Psoriatic arthritis is classified as one of the spondyloarthropathies — diseases affecting the joints of the spine. This same group of pathologies includes ankylosing spondylitis, Reiter's syndrome, and arthritis associated with chronic inflammatory bowel diseases.

All these conditions share a number of common features:

• Absence of rheumatoid factor (seronegativity).
• Genetic predisposition, manifested by an association with class I major histocompatibility complex antigens (specifically, HLA-B27).
• Early onset of clinical manifestations.
• Characteristic asymmetric involvement of the joint apparatus.
• Development of axial arthritis (joint syndrome involving the spine) and the presence of extra-articular manifestations, the most frequent of which is uveitis (eye inflammation).

Pathomorphology and Lesion Localization

The morphological basis of the complication is chronic serous inflammation of the synovial membrane of the joint. The inflammation is accompanied by active tissue proliferation and the formation of papillary outgrowths.

Microscopic picture:

• The synovial inflammatory infiltrate contains a large number of plasma cells, macrophages, and CD4 helper lymphocytes.
• The vessels of the synovium are markedly hyperemic, and typical inflammatory changes are found within them.
• During an exacerbation, the intra-articular fluid becomes turbid, and dense fibrin clots appear in it.

Topography of the pathological process: The disease is relapsing in nature. Most often, the small interphalangeal joints of the fingers and toes are the first to be affected. As it progresses, the inflammation spreads to large articulations: the ankle, knee, hip, and wrist joints. In 20–40% of patients, the sacroiliac and intervertebral joints are involved in the pathological process, forming the typical picture of axial arthritis.

Drug Therapy and Outcomes

Although the long-term course of arthritis can lead to pronounced stiffness of large joints requiring surgical intervention (up to resection and arthroplasty), timely therapy makes it possible to control symptoms.

One of the modern treatment regimens is the use of drugs whose mechanism of action is based on the inhibition of phosphodiesterase 4 (PDE-4). This indirectly blocks intracellular signaling pathways and reduces the production of key pro-inflammatory cytokines.

Features of PDE-4 inhibitor use:

• Niche: Monotherapy or in combination with methotrexate. The drug of choice for patients with metabolic disorders, diabetes mellitus, or a risk of infections (when other immunosuppressants are contraindicated).
• Efficacy: Demonstrates moderate efficacy in psoriasis, reducing symptoms of arthritis, dactylitis, and enthesitis. Especially indicated for mono- and oligoarticular forms in early stages.
• Safety: Possesses a favorable profile. Requires neither tuberculosis screening before therapy initiation nor continuous laboratory monitoring.

Dose titration schedule (daily increase):

1. Day 1: 10 mg (morning only).
2. Day 2: 10 mg morning + 10 mg evening.
3. Day 3: 10 mg morning + 20 mg evening.
4. Day 4: 20 mg morning + 20 mg evening.
5. Day 5: 20 mg morning + 30 mg evening.
6. Day 6 and onwards: maintenance dosage of 30 mg morning and evening.

Note: If the patient temporarily interrupted treatment, re-titration of the dose according to the schedule is not required.

Class and exam questions

What else to study on this topic

• Clinical and radiological picture of ankylosing spondylitis ("beggar's posture", "bamboo spine")
• Reiter's triad and its connection with infectious diseases
• Features of tuberculous bone and joint involvement (osteomyelitis)
• Migratory arthritis as a manifestation of systemic tick-borne borreliosis (Lyme disease)
• Mechanism of amyloidosis development in chronic inflammatory arthritides

Other topics in the "Rheumatic Diseases" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.