The term parapsoriasis was initially coined more than 100 years ago and included pityriasis lichenoides, large plaque parapsoriasis, and small plaque parapsoriasis, which exhibit a similar clinical appearance but different etiology from psoriasis [1] [2]. The conditions that fit the clinical and histological description of parapsoriasis seem to represent a spectrum of a lymphoproliferative disorder because many studies have established that patients with either small plaque or large plaque psoriasis eventually progress to a T-cell cutaneous lymphoma (known as mycosis fungoides) [2] [3] [4]. Furthermore, infectious pathogens, such as human herpesvirus type 8 (HHV-8), were identified in a substantial number of lesions [5], implying that microorganisms might play an important role in the development of this clinical entity. As mentioned previously, three main subtypes of parapsoriasis are currently identified [1] [4] [6] [7]:

• Pityriasis lichenoides - It is described as a rare disorder of the skin with several clinical forms - pityriasis lichenoides et varioliformis acuta (PLEVA), pityriasis lichenoides chronica (PLC) and febrile ulceronecrotic Mucha-Habermann disease (FUMHD) [7]. Main findings include an acute eruption of small red papules on multiple sites that may leave residual hypo/hyperpigmentation and scarring after resolution (PLEVA), a slower onset of flat macules and papules that are reddish-to-brown in color (PLC), or severe generalized eruption of necrotic plaques, ulcers, and purpuric lesions that has a 25% mortality rate (FUMHD) [7].
• Small plaque parapsoriasis - The appearance of small (< 5 cm in diameter), pruritic macules, plaques, and patches on the extremities and the trunk in a relapsing and remitting fashion is the hallmark of small plaque parapsoriasis [1] [6]. They are more frequently encountered in middle-aged adults and a predominance toward male gender is observed [1] [6]. Digitate dermatosis, a separate type of small plaque parapsoriasis, is described when symmetrically distributed finger-like patches develop on the flanks [6].
• Large plaque parapsoriasis - In addition to a larger diameter (> 5 cm, but many patients present with lesions of > 10 cm), atrophy of the plaques is a typical sign of large-plaque parapsoriasis. The lower extremities (thighs and buttocks), as well as the flexures of all extremities, are the main location where skin lesions appear [6]. Retiform parapsoriasis is a term used to describe a web-like disseminated pattern of lesions [1].

• Asymptomatic

  Abstract The term parapsoriasis refers to a group of chronic asymptomatic scaly dermatoses of unknown etiology about which there is still controversy over the nosology and nomenclature of the different conditions that comprise the group, particularly [ncbi.nlm.nih.gov]

  Associated with Hepatitis C virus infection[14] Sneddon–Wilkinson disease[15] Flaccid pustules that are often generalized and have a tendency to involve the flexural areas Annular configuration Pruritus May be asymptomatic Associated with: Monoclonal [wikidoc.org]

  Small plaque parapsoriasis is usually asymptomatic, treatment is prescribed to alleviate the dry lesions on the skin. The treatment for small plaque parapsoriasis include mid potency topical steroids, emollients or phototherapy. [dermpathdiagnostics.com]

  Parapsoriasis is sometimes asymptomatic and requires treatment to avoid the risk of cancer. Topical corticosteroids can be applied in the moderate form of small plaque parapsoriasis. [icliniq.com]

• Pathologist

  After inspection of the recorded files, the pathologists noted, were available, the localization and number of the lesions, together with symptoms. [ncbi.nlm.nih.gov]

  After histopathological features are evaluated by pathologists, dermoscopic correlations will be examined for each lesion. 30 patients with clinical and histopathological diagnosis of mycosis fungoides, and 30 patients with clinical and histopathological [clinicaltrials.gov]

  After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. [dovemed.com]

• Pallor

  Metabolism and nutrition system disorders : folate deficiency Renal and urinary disorders : nephrolithiasis Respiratory, thoracic and mediastinal disorders : oropharyngeal pain Skin and subcutaneous tissue disorders : angioedema, purpura Vascular disorders : pallor [rxlist.com]

• Cough

  […] sore Pruritus Musty odor Associated with: Infections (Fungal, bacterial, viral) Allergies Diabetes Obesity Langerhans cell histiocytosis[22] Scaling and crusting of scalp Pathological fractures[23] Visceromegaly (hepatomegaly, spleenomegaly) Chronic cough [wikidoc.org]

• Nausea

  SIDE EFFECTS The most common adverse reactions associated with sulfasalazine in ulcerative colitis are anorexia, headache, nausea, vomiting, gastric distress, and apparently reversible oligospermia. These occur in about one-third of the patients. [rxlist.com]

• Vomiting

  SIDE EFFECTS The most common adverse reactions associated with sulfasalazine in ulcerative colitis are anorexia, headache, nausea, vomiting, gastric distress, and apparently reversible oligospermia. These occur in about one-third of the patients. [rxlist.com]

• Myalgia

  […] lichenoides chronica Recurrent lesions are usually less evenly scattered than in cases of psoriasis Brownish red or orange-brown in color Lesions are capped by a single detachable, opaque, mica-like scale Often leave hypopigmented macules High fever Malaise Myalgias [wikidoc.org]

• Skin Disease

  […] pityriasis lichenoides. parapsoriasis (par´əsərī´əsis), n a group of chronic skin diseases resembling psoriasis, characterized by maculopapular, erythematous, scaly eruptions without systemic symptoms. [medical-dictionary.thefreedictionary.com]

  Cutaneous T cell lymphoma (CTCL) and reactive T cell skin diseases represent opposite ends of a spectrum of diseases ranging from overtly malignant to persistently benign. [ncbi.nlm.nih.gov]

  Prevention This skin disease can unfortunately not be prevented. [health.ccm.net]

• Eruptions

  After surgery, the skin eruptions disappeared completely in seven days and so a diagnosis of parapsoriasis syndrome was done. [ncbi.nlm.nih.gov]

  Eruptions are both psoriatic and lichenoid in appearance, but the diseases are distinct from psoriasis, lichen planus, or other recognized dermatoses. [icd10data.com]

  These eruptions had been described by different observers in different countries. [jamanetwork.com]

• Erythema

  As controls biopsies of patch test reactions, contact dermatitis, initial psoriasis, and erythema chronicum migrans were studied. [ncbi.nlm.nih.gov]

  […] was almost always seen within months. 3 In a more recent communication 4 Van Scott and Winters reported complete remissions of from two to nine months in 11 of 14 patients with plaque stage of mycosis fungoides and in 3 of 4 patients with generalized erythema [jamanetwork.com]

  The paraneoplastic cutaneous syndromes include reactive erythemas (erythema gyratum repens and necrolytic migratory erythema), vascular dermatoses (Trousseau's syndrome), papulosquamous disorders (acanthosis nigricans, tripe palms, palmar hyperkeratosis [wjso.biomedcentral.com]

• Skin Plaque

  Inverse -- Skin redness and irritation occurs in the armpits, groin, and in between overlapping skin. Plaque -- Thick, red patches of skin are covered by flaky, silver-white scales. This is the most common type of psoriasis. [checkorphan.org]

  Both skin conditions share symptoms such as plaques, which are scaly patches on the skin, and rashes. There are two types of parapsoriasis. Small plaque parapsoriasis (SPP) is a chronic, benign condition, meaning it is unlikely to become cancerous. [medicalnewstoday.com]

• Urticaria

  Less frequent adverse reactions are pruritus, urticaria, rash, fever, Heinz body anemia, hemolytic anemia and cyanosis, which may occur at a frequency of 1 in 30 patients or less. [rxlist.com]

• Irritability

  Overview Psoriasis is a common skin condition that causes skin redness and irritation. Most people with psoriasis have thick, red skin with flaky, silver-white patches called scales. Symptoms Psoriasis can appear suddenly or slowly. [checkorphan.org]

  Application of thin layer of aloe vera gel is useful in reducing the irritation. In order to reduce irritation patient must avoid scratching the area. A cool bath may be much more soothing. Avoid scrubbing and scratching the skin during bathing. [tandurust.com]

  Slight and chronic stimulation by certain xenobiotics may cause, at the very least, allergic contact dermatitis or irritant contact dermatitis. Their appearance may change to resemble the macula of mycosis fungoides (MF). [therapeutique-dermatologique.org]

A properly conducted physical examination and a meticulously obtained patient history are essential steps in making an initial diagnosis of parapsoriasis [6]. For this reason, physicians must obtain data regarding the progression of symptoms, their pattern of appearance (relapses, recurrences, etc.), and the location where they appear. A full inspection of the skin reveals crucial information about the lesions (their size, type, and stage), which is why the physical examination is perhaps the most important component of the workup. But because the diagnosis cannot be made solely on clinical grounds, and because progression to mycosis fungoides may occur in unrecognized patients (carrying a significantly poorer prognosis), a prompt sampling of the lesion and a histopathological evaluation is necessary. Small plaque parapsoriasis is distinguished by nonspecific epithelial hyperplasia, acanthosis, spongiosis, focal hyperkeratosis, and exocytosis [1] [6], whereas infiltration of lymphocytes, lichenoid findings, variable epithelial appearance (hyperplastic, atrophic, or even normal) and necrosis of keratinocytes are known hallmarks of large plaque parapsoriasis [1] [6]. However, lymphocytic infiltrates (although much milder) in the dermis have been identified in small plaque parapsoriasis as well [1], illustrating the frequent histological overlapping of the parapsoriasis subtypes.

METHODS: A retrospective study of treatment response in 116 patients diagnosed with MF and 71 patients with parapsoriasis and treated with topical nitrogen mustard from 1991 to 2009. [ncbi.nlm.nih.gov]

Parapsoriasis is resistant to all treatment. [medical-dictionary.thefreedictionary.com]

Although these various diseases have some similar clinical and histopathological features, they are obviously quite different from the standpoint of malignant potential and prognosis. [ncbi.nlm.nih.gov]

The prognosis of LPP is related to the progression and treatment of underlying mycoses fungoides Nevertheless, individuals with milder signs and symptoms have a better prognosis than those with severe signs and symptoms Regular follow up visits with the [dovemed.com]

The prognosis is excellent. [dermpedia.org]

The term applied to a group of relatively uncommon inflammatory, maculopapular, scaly eruptions of unknown etiology and resistant to conventional treatment. [icd10data.com]

[…] characterized by papules and plaques or scaly patches resembling psoriasis The term applied to a group of relatively uncommon inflammatory, maculopapular, scaly eruptions of unknown etiology and resistant to conventional treatment. [icd9data.com]

Abstract The term parapsoriasis refers to a group of chronic asymptomatic scaly dermatoses of unknown etiology about which there is still controversy over the nosology and nomenclature of the different conditions that comprise the group, particularly [ncbi.nlm.nih.gov]

Etiology and Pathophysiology LPP is a chronic inflammatory disorder likely caused by long-term stimulation of a specific subset of T cells by a corresponding antigen. [unboundmedicine.com]

Last updated : September 6, 2019 Summary Epidemiology References:[1][2][3] Epidemiological data refers to the US, unless otherwise specified. [amboss.com]

AIM: The aim of the study was to investigate the epidemiological and morphological data of parapsoriasis cases diagnosed at Emergency City Hospital, Timisoara, Romania for a period of 12 years. [ncbi.nlm.nih.gov]

Epidemiology No accurate statistics on the incidence and frequency Etiology Unknown Pathogenesis Develops from a few patches, which become more visible over time Clinical Small plaque – well-circumscribed, slightly scaly, light salmon-colored patches, [dermpathdiagnostics.com]

Epidemiology Incidence There are no good data reflecting the true incidence of LPP. [unboundmedicine.com]

Etiology and Pathophysiology LPP is a chronic inflammatory disorder likely caused by long-term stimulation of a specific subset of T cells by a corresponding antigen. [unboundmedicine.com]

PDF Downloads: 0 (Spandidos Publications: | PMC Statistics: ) Abstract It has recently been demonstrated that γδ T lymphocytes play a role in innate immunity to the neoplastic process; however, the significance of this subset of T lymphocytes in the pathophysiology [spandidos-publications.com]

Pathophysiology of Parapsoriasis The initiating cause of parapsoriasis is unknown, but the diseases likely represent different stages in a continuum of lymphoproliferative disorders from chronic dermatitis to frank malignancy of cutaneous T-cell lymphoma [emedicine.com]

General Prevention There are no known preventative measures. [unboundmedicine.com]

Prevention There is no known way to prevent psoriasis. Keeping the skin clean and moist and avoiding your specific psoriasis triggers may help reduce the number of flare-ups. Doctors recommend daily baths or showers for persons with psoriasis. [checkorphan.org]

Prevention This skin disease can unfortunately not be prevented. [health.ccm.net]

1. Baderca F, Chiticariu E, Baudis M, Solovan C. Biopsying parapsoriasis: quo vadis? Are morphological stains enough or are ancillary tests needed? Rom J Morphol Embryol. 2014;55(3 Suppl):1085-1092.
2. Sarveswari KN, Yesudian P. The conundrum of parapsoriasis versus patch stage of mycosis fungoides. Indian J Dermatol Venereol Leprol. 2009;75(3):229-235.
3. Väkevä L, Sarna S, Vaalasti A, Pukkala E, Kariniemi AL, Ranki A. A retrospective study of the probability of the evolution of parapsoriasis en plaques into mycosis fungoides. Acta Derm Venereol. 2005;85(4):318-323.
4. Salava A, Pereira P, Aho V, et al. Skin Microbiome in Small- and Large-plaque Parapsoriasis. Acta Derm Venereol. 2017 Feb 8.
5. Kreuter A, Bischoff S, Skrygan M, et al. High association of human herpesvirus 8 in large-plaque parapsoriasis and mycosis fungoides. Arch Dermatol. 2008;144(8):1011–1016.
6. Lewin J, Latkowski JA. Digitate dermatosis (small-plaque parapsoriasis). Dermatol Online J. 2012;18(12):3.
7. Khachemoune A, Blyumin ML. Pityriasis lichenoides: pathophysiology, classification, and treatment. Am J Clin Dermatol. 2007;8(1):29-36.