Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 4 complete abstracts (1,021 words), 10 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
The term applied to a group of relatively uncommon inflammatory, maculopapular, scaly eruptions of unknown etiology and resistant to conventional treatment. Eruptions are both psoriatic and lichenoid in appearance, but the diseases are distinct from psoriasis, lichen planus, or other recognized dermatoses. Proposed nomenclature divides parapsoriasis into two distinct subgroups, pityriasis lichenoides and parapsoriasis en plaques (small- and large-plaque parapsoriasis).
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Parapsoriases; Digitate Dermatosis; Dermatoses, Digitate; Dermatosis, Digitate; Digitate Dermatoses; Erythroderma, Maculopapular; Erythrodermas, Maculopapular; Maculopapular Erythroderma.
Where it fits in the MeSH classification
- Broader topics
- Skin Diseases, Papulosquamous
- Narrower topics
- Pityriasis Lichenoides
Related concepts
Research landscape
PubMed indexes 1,107 records tagged with the MeSH heading “Parapsoriasis” (counts retrieved 2026-11-04). 103 of them (9.3%) were published from 2020 onward, and the busiest period so far is through 1999 with 648 records.
Reviews account for 76 records (6.9%) and meta-analyses for 0. Randomized controlled trials number 3 (0.3%) as a share of all records on the topic. Randomized trials make up only a small share of this literature, so much of what is known comes from laboratory, observational or descriptive work.
Show the data
| Period | Records |
|---|---|
| through 1999 | 648 |
| 2000-2009 | 168 |
| 2010-2019 | 188 |
| 2020 onward | 103 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 76 | 6.9% |
| Meta-analyses | 0 | 0.0% |
| Randomized controlled trials | 3 | 0.3% |
Method: PubMed query "Parapsoriasis"[MeSH Terms] with publication-type and date filters, retrieved 2026-11-04.
Reading the evidence in bones, joints, muscles and skin
Joint, bone, muscle and skin conditions are often judged by pain scores, function questionnaires, imaging or photographs, and symptoms can fluctuate, so placebo response and natural improvement matter. Imaging changes are common in people without symptoms. Nothing on this page is advice about treatment. Check how outcomes were measured, whether the comparison group received a placebo or usual care, and how long the benefit lasted.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
Positive effects of hydrogen-water bathing in patients of psoriasis and parapsoriasis en plaques [1]
Abstract reading summary — source excerpts
- Opening excerpt
- Psoriasis and parapsoriasis en plaques are chronic inflammatory skin diseases, both representing therapeutic challenge in daily practice and adversely affecting the quality of life.
- Closing excerpt
- Our findings suggested that hydrogen-water bathing therapy could fulfill the unmet need for these chronic inflammatory skin diseases.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (205 words)
Psoriasis and parapsoriasis en plaques are chronic inflammatory skin diseases, both representing therapeutic challenge in daily practice and adversely affecting the quality of life. Reactive oxygen species (ROS) has been evidenced to be involved in the pathogenesis of the chronic inflammatory diseases. We now report that hydrogen water, an effective ROS scavenger, has significant and rapid improvement in disease severity and quality of life for patients with psoriasis and parapsoriasis en plaques. At week 8, our parallel-controlled trial revealed 24.4% of patients (10/41) receiving hydrogen-water bathing achieved at least 75% improvement in Psoriasis Area Severity Index (PASI) score compared with 2.9% of patients (1/34) of the control group (Pc = 0.022, OR = 0.094, 95%CI = [0.011, 0.777]). Of patients, 56.1% (23/41) who received bathing achieved at least 50% improvement in PASI score compared with only 17.7%(6/34) of the control group (P = 0.001, OR = 0.168, 95%CI = [0.057, 0.492]). The significant improvement of pruritus was also observed (P = 3.94 × 10-4). Besides, complete response was observed in 33.3% of patients (2/6) of parapsoriasis en plaques and partial response in 66.7% (4/6) at week 8. Our findings suggested that hydrogen-water bathing therapy could fulfill the unmet need for these chronic inflammatory skin diseases.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 29795283 · DOI · PMC5966409
From SARS-CoV-2 hematogenous spreading to endothelial dysfunction: clinical-histopathological study of cutaneous signs of COVID-19 [2]
Abstract reading summary — source excerpts
- Opening excerpt
- BackgroundTo date, very few studies on clinical-histopathological correlations of cutaneous disorders associated with COVID-19 have been conducted.
- Closing excerpt
- We speculate that a purpuric rash could represent the cutaneous sign of a more severe coagulopathy, as highlighted histologically by vascular abnormalities, while a sub-erythroderma could be expression of viral hematogenous spreading, inducing a non-specific chronic dermatitis.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (344 words)
BackgroundTo date, very few studies on clinical-histopathological correlations of cutaneous disorders associated with COVID-19 have been conducted.Case presentationThe Case 1 was a 90-year-old man, who tested positive for SARS-CoV-2 from a nasopharyngeal swab. Two days later, he was hospitalized and after eleven days transferred to Intensive Care Unit. A chest CT showed bilateral ground-glass opacities. Just that day, an erythematous maculo-papular rash appeared on trunk, shoulders and neck, becoming purpuric after few days. Histological evaluations revealed a chronic superficial dermatitis with purpuric aspects. The superficial and papillary dermis appeared edematous, with a perivascular lympho-granulocytic infiltrate and erythrocytic extravasation. At intraepithelial level, spongiosis and a granulocyte infiltrate were detected. Arterioles, capillaries and post-capillary venules showed endothelial swelling and appeared ectatic. The patient was treated with hydroxychloroquine, azithromycin, lopinavir-ritonavir and tocilizumab. Regrettably, due to severe lung impairment, he died. The Case 2 was a 85-year-old man, admitted to Intensive Care Unit, where he was intubated. He had tested positive for SARS-CoV-2 from a nasopharyngeal swab two days before. A chest RX showed bilateral atypical pneumonia. After seven days, a cutaneous reddening involving trunk, upper limbs, neck and face developed, configuring a sub-erythroderma. Histological evaluations displayed edema in the papillary and superficial reticular dermis, and a perivascular lymphocytic infiltrate in the superficial dermis. The patient was treated with hydroxychloroquine, azithromycin, lopinavir-ritonavir and tocilizumab. Sub-erythroderma as well as respiratory symptoms gradually improved until healing.ConclusionsThe endothelial swelling detected in the Case 1 could be a morphological expression of SARS-CoV-2-induced endothelial dysfunction. We hypothesize that cutaneous damage could be initiated by endothelial dysfunction, caused by SARS-CoV-2 infection of endothelial cells or induced by immune system activation. The disruption of endothelial integrity could enhance microvascular permeability, extravasation of inflammatory cells and cytokines, with cutaneous injury. The Case 2 developed a sub-erythroderma associated with COVID-19, and a non-specific chronic dermatitis was detected at histological level. We speculate that a purpuric rash could represent the cutaneous sign of a more severe coagulopathy, as highlighted histologically by vascular abnormalities, while a sub-erythroderma could be expression of viral hematogenous spreading, inducing a non-specific chronic dermatitis.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 33632250 · DOI · PMC7905980
From Benign Inflammatory Dermatosis to Cutaneous Lymphoma. DNA Copy Number Imbalances in Mycosis Fungoides versus Large Plaque Parapsoriasis [3]
Abstract reading summary — source excerpts
- Opening excerpt
- Background and Objectives: Mycosis fungoides (MF) and large plaque parapsoriasis (LPP) evolution provide intriguing data and are the cause of numerous debates.
- Closing excerpt
- The similarity between these two pathologies in terms of CNAs is striking, emphasizing once again the difficulty of approaching and differentiating them.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (242 words)
Background and Objectives: Mycosis fungoides (MF) and large plaque parapsoriasis (LPP) evolution provide intriguing data and are the cause of numerous debates. The diagnosis of MF and LPP is associated with confusion and imprecise definition. Copy number alterations (CNAs) may play an essential role in the genesis of cancer out of genes expression dysregulation. Objectives: Due to the heterogeneity of MF and LPP and the scarcity of the cases, there are an exceedingly small number of studies that have identified molecular changes in these pathologies. We aim to identify and compare DNA copy number alterations and gene expression changes between MF and LPP to highlight the similarities and the differences between these pathologies. Materials and Methods: The patients were prospectively selected from University Clinic of Dermatology and Venereology Timișoara, Romania. From fresh frozen skin biopsies, we extracted DNA using single nucleotide polymorphism (SNP) data. The use of SNP array for copy number profiling is a promising approach for genome-wide analysis. Results: After reviewing each group, we observed that the histograms generated for chromosome 1-22 were remarkably similar and had a lot of CNAs in common, but also significant differences were seen. Conclusions: This study took a step forward in finding out the differences and similarities between MF and LPP, for a more specific and implicitly correct approach of the case. The similarity between these two pathologies in terms of CNAs is striking, emphasizing once again the difficulty of approaching and differentiating them.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 34063545 · DOI · PMC8156635
Exploring the Immune Microenvironment in Early-Stage Mycosis Fungoides and Large-Plaque Parapsoriasis: Diagnostic and Prognostic Significance of CD47, CD163, and B7-H3 [4]
Abstract reading summary — source excerpts
- Opening excerpt
- Background and Objectives: Mycosis fungoides (MF) is the predominant subtype of cutaneous T-cell lymphoma, whereas large plaque parapsoriasis (LPP) closely resembles early-stage MF, making differential diagnosis challenging.
- Closing excerpt
- 7% compared with LPP patients (p Conclusions: The higher expression of CD47, CD163, and B7-H3 in early-stage MF compared with LPP suggests that these markers may contribute to the differential diagnosis and could represent potential therapeutic targets; however, their independent prognostic value requires confirmation in larger studies.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (230 words)
Background and Objectives: Mycosis fungoides (MF) is the predominant subtype of cutaneous T-cell lymphoma, whereas large plaque parapsoriasis (LPP) closely resembles early-stage MF, making differential diagnosis challenging. Immune markers, such as CD47, CD163, and B7-H3, play crucial roles in tumor immune evasion and macrophage polarization. However, their expression profiles and potential diagnostic or prognostic implications in early-stage MF and LPP remain poorly defined. Therefore, this study aimed to evaluate the expression of CD47, CD163, and B7-H3 in early-stage MF and LPP and analyze their associations with clinicopathological characteristics and patient outcomes. Materials and Methods: This retrospective study evaluated the immunohistochemical expression of CD47, CD163, and B7-H3 in 46 patients with early-stage mycosis fungoides (MF) and 46 patients with large plaque parapsoriasis (LPP). Expression levels were assessed using an immunoreactivity scoring system and analyzed for their associations with clinical parameters and disease-free survival (DFS). The study included patients diagnosed and followed at Sivas Cumhuriyet University between 1 March 2015 and 31 March 2025. Results: High CD47 expression was detected in 72.7% of MF patients, high B7-H3 expression in 45.7%, and high CD163 expression in 46.7% compared with LPP patients (p Conclusions: The higher expression of CD47, CD163, and B7-H3 in early-stage MF compared with LPP suggests that these markers may contribute to the differential diagnosis and could represent potential therapeutic targets; however, their independent prognostic value requires confirmation in larger studies.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42075550 · DOI · PMC13118023
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Pityriasis lichenoides and its subtypes [5]
- Research article Pityriasis lichenoides: pathophysiology, classification, and treatment [6]
- Research article The nosology of parapsoriasis [7]
- Research article Transition of pityriasis lichenoides et varioliformis acuta to febrile ulceronecrotic Mucha-Habermann disease is associated with elevated serum tumour necrosis factor-alpha [8]
- Research article Infectious causes of pityriasis lichenoides: a case of fulminant infectious mononucleosis [9]
- Research article A systematic review of treatments for pityriasis lichenoides [10]
References
- Zhu Q, Wu Y, Li Y, Chen Z, Wang L, Xiong H, et al.. Positive effects of hydrogen-water bathing in patients of psoriasis and parapsoriasis en plaques. . 2018. PMID 29795283 · DOI · PMC5966409
- Patrì A, Vargas M, Buonanno P, Annunziata MC, Russo D, Staibano S, et al.. From SARS-CoV-2 hematogenous spreading to endothelial dysfunction: clinical-histopathological study of cutaneous signs of COVID-19. . 2021. PMID 33632250 · DOI · PMC7905980
- Gug G, Solovan C. From Benign Inflammatory Dermatosis to Cutaneous Lymphoma. DNA Copy Number Imbalances in Mycosis Fungoides versus Large Plaque Parapsoriasis. . 2021. PMID 34063545 · DOI · PMC8156635
- Yasak Guner R, Yüceer RO, Unsal AT. Exploring the Immune Microenvironment in Early-Stage Mycosis Fungoides and Large-Plaque Parapsoriasis: Diagnostic and Prognostic Significance of CD47, CD163, and B7-H3. . 2026. PMID 42075550 · DOI · PMC13118023
- Bowers S, Warshaw EM. Pityriasis lichenoides and its subtypes. J Am Acad Dermatol. 2006. PMID 17010734 · DOI
- Khachemoune A, Blyumin ML. Pityriasis lichenoides: pathophysiology, classification, and treatment. Am J Clin Dermatol. 2007. PMID 17298104 · DOI
- Lambert WC, Everett MA. The nosology of parapsoriasis. J Am Acad Dermatol. 1981. PMID 7026622 · DOI
- Tsianakas A, Hoeger PH. Transition of pityriasis lichenoides et varioliformis acuta to febrile ulceronecrotic Mucha-Habermann disease is associated with elevated serum tumour necrosis factor-alpha. Br J Dermatol. 2005. PMID 15840118 · DOI
- Klein PA, Jones EC, Nelson JL, Clark RA. Infectious causes of pityriasis lichenoides: a case of fulminant infectious mononucleosis. J Am Acad Dermatol. 2003. PMID 12894107 · DOI
- Bellinato F, Maurelli M, Gisondi P, Girolomoni G. A systematic review of treatments for pityriasis lichenoides. J Eur Acad Dermatol Venereol. 2019. PMID 31318465 · DOI
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-11-04; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-11-04.
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Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.