Page 150 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 4-65 Integumentary System

PSORIATIC ARTHRITIS

PSORIASIS (Continued)

clues to the pathogenesis of psoriasis. Psoriatic patients
given this medicine almost always have rapid clinical
improvement.
T-cell lymphocytes and dermal dendritic cells are the
most likely precursor cells to be the cause of psoriasis; Pitting, discoloration, and erosion
they are both found in increased numbers in psoriatic of fingernails with fusiform swelling
plaques. CD8+ T cells are the predominant lymphocyte of distal interphalangeal joints
found within the epidermis; they contain the cutaneous
lymphocyte antigen (CLA) antigen on their cell surface.
The CLA antigen is important because it directs these
cells into the skin. Many subsets of dermal dendritic
cells have been found within psoriatic plaques. Den-
dritic cells have been shown to be potent stimulators of Psoriatic patches on dorsum of hand
T cells, and they are believed to be required to propa- with swelling and distortion of many
gate the inflammatory reaction. These two cell types interphalangeal joints and shortening
interact with each other and change the local cytokine of fingers due to loss of bone mass
profile into one that is proinflammatory and provides a
milieu that is required for the development of the clini-
cal findings of psoriasis. What is still unknown is the
initial stimulus that sets off this cascade of events and
how it is propagated and perpetuated. Radiographic changes in distal inter-
Histology: Histological examination of biopsy phalangeal joint. Left, In early stages, bone
specimens of psoriasis vulgaris show regular erosions are seen at joint margins. Right, In
psoriasiform hyperplasia of the epidermis. Multiple late stages, further loss of bone mass
normal-appearing mitotic figures are seen within kera- produces “pencil point in cup” appearance.
tinocytes. Neutrophils are prominent within the
stratum corneum and within the lumen of the papillary
dermal blood vessels. Mounds of parakeratosis are seen
in the stratum corneum and contain many neutrophils.
The papillary dermis shows a proliferation of ectatic
capillary vessels with a perivascular infiltrate made up
of lymphocytes, Langerhans cells, and histiocytes. Col-
lections of neutrophils within the stratum corneum are
called Munro microabscesses. Kogoj microabscesses are
similar collections of neutrophils within the stratum
spinosum. There is a decrease in the thickness of the
granular cell layer. With time, some of the tips of the
rete ridges coalesce and form thickened ends.
Pustular psoriasis shows varying amounts of intraepi-
dermal pustules; acanthosis and psoriasiform hyperpla-
sia are not prominent. Again, there are multiple dilated
capillary blood vessels in the papillary dermis.
Treatment: There is no cure for psoriasis. Treatment Radiograph of sacroiliac joints shows thin
should be based on the amount and location of the cartilage with irregular surface and
psoriatic plaques and consideration of the psychological Toes with sausage-like swelling, condensation of adjacent bone in
well-being of the affected individual. Small areas in skin lesions, and nail changes sacrum and ilia.
discrete locations can be treated with topical corticoste-
roids, anthralin, tar compounds, or vitamin D or A
analogues or left alone without therapy. Ultraviolet
therapy with natural sunlight, narrow-band ultraviolet with excellent results. In the long term, these therapies available over the last decade. These medications are
B light (UVB), or psoralen + ultraviolet A light (PUVA) increase the patient’s risk of developing skin cancers, given by subcutaneous, intramuscular, or intravenous
has been used with great success. Often, combinations and lifelong dermatologic follow-up is required. injection. They include etanercept, alefacept, adalim-
of therapies are implemented. Oral systemic agents are also used for moderate to umab, infliximab, and ustekinumab. All of these agents
As the body surface area of involvement increases or severe psoriasis. Methotrexate taken on a weekly basis have had excellent response rates. They are all consid-
the psychological well-being of the individual is affected has been used for years. Oral cyclosporine has been ered to be immunosuppressive, and patients taking
such that systemic therapy is warranted, many agents used with great success for erythrodermic and pustular these medications need close clinical follow-up, because
are available to treat the psoriasis. Phototherapy with psoriasis. Its use is limited to 6 to 12 months because they are at increased risk for infections and possibly for
narrow-band UVB or PUVA has been used for decades of nephrotoxicity. Many biological agents have become systemic cancers, such as lymphoma, after years of use.

136 THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS