Inverse psoriasis or flexural psoriasis is a form of

psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by patches of abnormal skin. These areas are red, pink, or purple, dry, itchy, and scaly. Psoriasis varies in severity from small localized patches to complete b ...

that selectively, and often exclusively, involves the folds, recesses, and flexor surfaces such as the ears,

axilla The axilla (: axillae or axillas; also known as the armpit, underarm or oxter) is the area on the human body directly under the shoulder joint. It includes the axillary space, an anatomical space within the shoulder girdle between the arm a ...

e, groin folds, inframammary folds,

navel The navel (clinically known as the umbilicus; : umbilici or umbilicuses; also known as the belly button or tummy button) is a protruding, flat, or hollowed area on the abdomen at the attachment site of the umbilical cord. Structure The u ...

, intergluteal cleft,

penis A penis (; : penises or penes) is a sex organ through which male and hermaphrodite animals expel semen during copulation (zoology), copulation, and through which male placental mammals and marsupials also Urination, urinate. The term ''pen ...

, and lips.James, William; Berger, Timothy; Elston, Dirk (2005). ''Andrews' Diseases of the Skin: Clinical Dermatology''. (10th ed.). Saunders. .

Signs and symptoms

Well-defined, erythematous patches are the clinical hallmark of inverse psoriasis. The perianal area, umbilicus, axillae, inframammary folds, inguinal folds, and retroauricular areas are the areas most frequently affected. Interdigital spaces and the popliteal and antecubital fossae may also be affected. In contrast to

plaque psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by patches of abnormal skin. These areas are red, pink, or purple, dry, itchy, and scaly. Psoriasis varies in severity from small localized patches to complete b ...

, the lesions' surface appears wet, smooth, and shiny, and yellowish scales are usually minor or absent.

Causes

Psoriasis is a cellular autoimmune reaction caused by

T-cells T cells (also known as T lymphocytes) are an important part of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell receptor (TCR) on their cell ...

to what are thought to be skin-resident self-antigens. The psoriasiform reaction is brought on by an increase in interferon-γ and interleukin-17, which interact with

mast cells A mast cell (also known as a mastocyte or a labrocyte) is a resident cell of connective tissue that contains many granules rich in histamine and heparin. Specifically, it is a type of granulocyte derived from the myeloid stem cell that is a ...

, neutrophils,

macrophages Macrophages (; abbreviated MPhi, φ, MΦ or MP) are a type of white blood cell of the innate immune system that engulf and digest pathogens, such as cancer cells, microbes, cellular debris and foreign substances, which do not have proteins that ...

, and dermal cells. There is little evidence to suggest that the pathophysiologic mechanisms underlying inverse and common psoriasis vary from one another. The amount of CD161+ cells in the inverse psoriasis plaques, however, might be diminishing. This is thought to be caused by the ongoing microbial colonization of the inverse psoriasis-affected regions.

Diagnosis

The diagnosis of inverse psoriasis is typically clinical, and a physical examination should check for

in other parts of the body besides skin folds, such as mucosae. When inverse psoriasis is the sole symptom of the illness, diagnosis might be challenging in certain situations and necessitate skin biopsies. In terms of histopathology, inverse psoriasis exhibits the typical pattern of

, which includes rete ridge elongation and epidermal hyperplasia along with parakeratosis, acanthosis, suprapapillary plate thinning, granulosus layer reduction, and, in certain situations, Munro microabcesses and Kogoj micropustules. Spongiosis is more widespread and epidermal hyperplasia is less prominent than in classical plaque psoriasis.

Treatment

The cornerstone of treatment for all types of psoriasis, including inverse psoriasis, is topical corticosteroids.

References

External links

DermNet

Cleveland Clinic
{{Papulosquamous disorders Psoriasis