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  1. Article ; Online: Nail Telocytes: Identification, Potential Physiological Function, and Role in Pathology: A Reappraisal of the So-Called Onychofibroblasts/Onychodermis.

    Perrin, Christophe

    The American Journal of dermatopathology

    2024  

    Abstract: Abstract: Some authors have suggested that the fibroblasts of the nail mesenchyme (onychofibroblasts) can be distinguished from skin fibroblasts by their high expression of CD10. My 2015 study documented the presence of a relatively sparse CD34+/CD10+ ... ...

    Abstract Abstract: Some authors have suggested that the fibroblasts of the nail mesenchyme (onychofibroblasts) can be distinguished from skin fibroblasts by their high expression of CD10. My 2015 study documented the presence of a relatively sparse CD34+/CD10+ dendritic subpopulation in the dermis and hypodermis of the matrix. For some time now, my hypothesis has been that these interstitial dendritic mesenchymal cells of the matrix correspond to telocytes. Telocytes have been described as peculiar interstitial dendritic cells present in the mesenchymal tissue of numerous organs, including the skin, but their presence and characteristics in the nail unit have not been explored. This study was undertaken to more comprehensively investigate the existence and characteristics of nail telocytes. A series of 20 normal adult nail units were examined with a combination of morphological and immunohistochemical analyses. The matrix dermis contained a sparse subpopulation of CD34+/CD10+ elongated telocytes with a higher density in the lunular region and, at this distal level, a change in their immunohistochemical profile, resulting in a progressive loss of CD34 expression. The matrix hypodermis showed CD34+/CD10+ telocytes in their classical elongated aspect, which acquired, especially in the distal fibromyxoid area of the thumb, an oval to round morphology with multiple intracytoplasmic vacuoles. The characteristic dynamic immunophenotypic profile of the dermal telocytes with a progressive distal loss of the defining molecule CD34 was equally observed in the distal hypodermis. The nail bed dermis was thick with a dense fibrous connective tissue. A reticular network of CD34-/CD10+ telocytes was present in the superficial dermis of the proximal nail bed. The mesenchymal cells of the deep part of the proximal nail bed dermis and the entire distal nail bed dermis were CD34-/CD10-. The adult nail mesenchyme is composed of 3 microanatomically distinct regions. Only the thumb has a distal hypodermis rich in mucinous material. The population of telocytes is relatively sparse compared with the fibroblastic population of the entire nail mesenchyme. The concept of onychodermis/onychofibroblasts is not valid. Nail telocytes have a dynamic immunohistochemical profile depending on whether they are located proximally or distally. The CD34+/CD10+ profile correlates with the onychogenic epithelial region, while the CD34-/CD10+ profile correlates with a spatial rearrangement of the nail epidermal bed.
    Language English
    Publishing date 2024-04-04
    Publishing country United States
    Document type Journal Article
    ZDB-ID 448469-1
    ISSN 1533-0311 ; 0193-1091
    ISSN (online) 1533-0311
    ISSN 0193-1091
    DOI 10.1097/DAD.0000000000002704
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Onychomatricoma Versus Superficial Acral Fibromyxoma: Nestin Immunohistochemistry Is a Help in the Differential Diagnosis.

    Perrin, Christophe

    The American Journal of dermatopathology

    2024  Volume 46, Issue 5, Page(s) 328–329

    MeSH term(s) Humans ; Nestin ; Diagnosis, Differential ; Immunohistochemistry ; Fibroma/diagnosis ; Soft Tissue Neoplasms/diagnosis ; Nail Diseases/diagnosis
    Chemical Substances Nestin
    Language English
    Publishing date 2024-02-07
    Publishing country United States
    Document type Journal Article
    ZDB-ID 448469-1
    ISSN 1533-0311 ; 0193-1091
    ISSN (online) 1533-0311
    ISSN 0193-1091
    DOI 10.1097/DAD.0000000000002628
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Are There Signs of Enthesitis in Nail Psoriasis? An Immunohistological Study of Nail Psoriasis With and Without Psoriatic Arthritis.

    Perrin, Christophe

    The American Journal of dermatopathology

    2022  Volume 45, Issue 1, Page(s) 40–46

    Abstract: Abstract: The concept of nail psoriasis as an entheseal-driven disease has essentially been formulated on the basis of radiological findings because it is usually not possible to obtain the tissue directly from the joints. The aim of this retrospective ... ...

    Abstract Abstract: The concept of nail psoriasis as an entheseal-driven disease has essentially been formulated on the basis of radiological findings because it is usually not possible to obtain the tissue directly from the joints. The aim of this retrospective study was to evaluate the histological features of isolated nail psoriasis with and without distal interphalangeal psoriatic arthritis (PsA), focusing on the question as to whether the fascia and adipose tissue surrounding the apex of the nail unit genuinely show an inflammatory infiltrate. In support of the nail-enthesitis theory, an ongoing inflammatory infiltrate could be expected. An immunohistochemical study was performed to evaluate the distribution and phenotype of the inflammatory infiltrate in nail psoriasis with and without PsA. This study did not show an inflammatory infiltrate in the fascia connecting the nail to the extensor tendon. CD8 and CD4 subsets were present in equal number in the nail dermis of nail psoriasis with or without PsA, which is a similar distribution to that seen in psoriatic synovium while skin psoriasis is characterized by a dermal predominance of CD4 T lymphocytes. Because of this study and recent microanatomic studies of the normal nail unit, it is possible to move away from a purely anatomic explanation of the strong association between nail psoriasis and PsA and to propose immunological factors as contributory. This study provides support for the hypothesis that CD8+ T cells play a crucial role in the pathogenesis of nail psoriasis through a pathogenic pathway similar to that of PsA and contrasting with that of the skin.
    MeSH term(s) Humans ; Arthritis, Psoriatic/complications ; Retrospective Studies ; Enthesopathy/complications ; Nail Diseases/pathology ; Psoriasis/complications
    Language English
    Publishing date 2022-12-07
    Publishing country United States
    Document type Journal Article
    ZDB-ID 448469-1
    ISSN 1533-0311 ; 0193-1091
    ISSN (online) 1533-0311
    ISSN 0193-1091
    DOI 10.1097/DAD.0000000000002328
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Preferentially Expressed Nuclear Antigen in Melanoma Expression in Melanocytic Activation (Melanotic Macule) of the Nail Unit. A Potential Diagnostic Pitfall? A Study of 3 Cases.

    Perrin, Christophe

    The American Journal of dermatopathology

    2022  Volume 44, Issue 7, Page(s) 499–502

    Abstract: Abstract: Recent studies have argued that melanocyte preferentially expressed nuclear antigen in melanoma (PRAME) is a sensitive and specific immunohistochemical marker of melanoma, including acral melanoma. In addition, loss of p16 expression has ... ...

    Abstract Abstract: Recent studies have argued that melanocyte preferentially expressed nuclear antigen in melanoma (PRAME) is a sensitive and specific immunohistochemical marker of melanoma, including acral melanoma. In addition, loss of p16 expression has recently been suggested to have diagnostic utility in acral melanocytic tumors. The purpose of this study was to report PRAME expression in 3 cases of melanocytic activation (MAN). There were 2 men and 1 woman ranging in age at diagnosis from 46 years to 78 years (mean 61, 6 years). All cases involved a single digit. One lesion was in the fingernail (fifth finger), whereas the remaining 2 lesions were in the toenails (hallux). All the patient presented with a longitudinal melanonychia. The width of the lesions varied from 3 mm (2 cases) to 4 mm (1 case). The duration of the lesions before diagnosis varied from 12 to 24 months. Distinction of MAN from melanoma in situ is not always easy. Some morphological misleading features are illustrated in this study: (1) the suprabasal location of matrix melanocytes with long and thick dendrites within the 2-4 germinative cell layers; (2) the microconfluence of 2 melanocytes and rare melanocytes with a relatively large nucleus, however in a general context of melanocyte scarcity; and (3) the occasional nonspecific nuclear microphtalmia-associated transcription factor (MITF) staining of keratogeneous cells. Such staining could suggest a pagetoid spread of melanocytes in the keratogenous zone. PRAME antibody revealed a strong and diffuse staining in all cases. In addition, all cases were p16 negative. In this study, the melanocyte count inferior to 9 melanocytes/mm and the lack of nuclear atypia or confluence of melanocytes permitted a confident diagnosis of MAN. Limitations of our study lie largely in the small number of cases. Despite this, the expression of PRAME in some MAN seems to hamper its diagnostic value in differentiating benign from malignant lesion.
    MeSH term(s) Aged ; Antigens, Neoplasm/metabolism ; Antigens, Nuclear ; Female ; Humans ; Male ; Melanocytes/pathology ; Melanoma/pathology ; Middle Aged ; Nails/pathology ; Skin Neoplasms/pathology ; Melanoma, Cutaneous Malignant
    Chemical Substances Antigens, Neoplasm ; Antigens, Nuclear ; PRAME protein, human
    Language English
    Publishing date 2022-02-25
    Publishing country United States
    Document type Case Reports ; Journal Article
    ZDB-ID 448469-1
    ISSN 1533-0311 ; 0193-1091
    ISSN (online) 1533-0311
    ISSN 0193-1091
    DOI 10.1097/DAD.0000000000002156
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Focal Synovial Inflammation Versus Enthesitis Theory in Distal Psoriatic Arthritis: A Pioneer Histopathologic Study.

    Perrin, Christophe

    The American Journal of dermatopathology

    2021  Volume 43, Issue 12, Page(s) 898–902

    Abstract: Abstract: The aim of this analysis was to re-examine the classical concept of distal interphalangeal joint (DIP) psoriatic arthritis (PsA) as an entheseal-driven disease. Two cadaveric fingers with severe psoriatic arthritis were analyzed. Our results ... ...

    Abstract Abstract: The aim of this analysis was to re-examine the classical concept of distal interphalangeal joint (DIP) psoriatic arthritis (PsA) as an entheseal-driven disease. Two cadaveric fingers with severe psoriatic arthritis were analyzed. Our results demonstrate that inflammation of DIP PsA is multifocal without interconnection between entheses and articular cartilage of the DIP. We found a clear association between synovitis and focal loss of articular cartilage at the head of the intermediate phalanx. By contrast, the articular cartilage adjacent to the zone of severe enthesitis did not show notable damage. Fibrocartilaginous destructions of enthesis were characterized by either a multifocal lymphocytic inflammation, accompanied by osteoclastic resorption, beginning on the interface between the uncalcified and calcified fibrocartilage and then extending into the bone or a subchondral bone inflammation which insidiously destroyed first the bone and then the fibrocartilage. Some sections well showed an inflammation either mild or prominent starting at the level of vascular foramina of flexor enthesis, with secondary invading into the interface between bone and enthesis. The different anatomic sites examined showed a slight predominance of CD8+ T cells over CD4+ T cells: 52% up to 63% for CD8+ T cells vs. to 36% up to 48% for CD4+ T cells. Sparse interspersed CD1a+cells and PS100+cells were also seen with a predominance of PS100+ cells on CD1a+ cells. CD20+ B cells, plasmocytes, neutrophils, and mastocytes were absent or rare. CD123 positive cells were not observed. In DIP PsA, 3 findings predominate: (1) cartilage invasion by the thin pannus offers a more rational explanation for the focal joint destruction than does inflammation of the enthesis which is independent from articular cartilage, (2) the thick ventral plate and to a lesser extend the thin dorsal plate constitute a barrier between the inflamed entheses and the articular cartilage, and (3) an unusual form of minute vascular foramen contributes to the early stage of enthesitis. This small study suggests that DIP PsA is a complex disease. It affects anatomical micro sites which, although close, are in fact relatively independent of each other. Further studies are needed to test this hypothesis.
    MeSH term(s) Arthritis, Psoriatic/pathology ; Enthesopathy/pathology ; Finger Joint/pathology ; Humans ; Synovitis/pathology
    Language English
    Publishing date 2021-04-06
    Publishing country United States
    Document type Journal Article
    ZDB-ID 448469-1
    ISSN 1533-0311 ; 0193-1091
    ISSN (online) 1533-0311
    ISSN 0193-1091
    DOI 10.1097/DAD.0000000000001947
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Onychomatricoma is not a subtype of superficial acral fibromyxoma: Can immunohistochemistry help in the differential diagnosis?

    Perrin, Christophe / Coutts, Michael

    Journal of cutaneous pathology

    2024  

    Language English
    Publishing date 2024-03-25
    Publishing country United States
    Document type Journal Article
    ZDB-ID 187078-6
    ISSN 1600-0560 ; 0303-6987
    ISSN (online) 1600-0560
    ISSN 0303-6987
    DOI 10.1111/cup.14616
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Histological Evaluation of the Relationships Between Distal Interphalangeal Psoriatic Arthritis and Nail Psoriasis: Correlations With Anatomical Studies of the Normal Nail Unit and the Main Radiological Data Concerning Distal Interphalangeal Psoriatic Arthritis.

    Perrin, Christophe

    The American Journal of dermatopathology

    2020  Volume 42, Issue 12, Page(s) 911–915

    Abstract: To determine whether distal interphalangeal joint psoriatic arthritis (DIP PsA) and nail psoriasis are anatomically linked, we studied 2 fingers taken from a cadaver presenting a typical cutaneous and nail psoriasis in the setting of a dactylitis limited ...

    Abstract To determine whether distal interphalangeal joint psoriatic arthritis (DIP PsA) and nail psoriasis are anatomically linked, we studied 2 fingers taken from a cadaver presenting a typical cutaneous and nail psoriasis in the setting of a dactylitis limited to the fourth toe. This comprehensive study of the inflammatory pattern of DIP PsA is discussed in the context of the controversial theory of the nail as a musculoskeletal appendage. Both the extensor and flexor entheses were focally and quite markedly infiltrated by lymphocytes and showed variable fibrosis and neovascularization. In addition, some clusters of giant cells were seen. Synovial perivascular inflammation was focally relatively dense. Discrete periostitis and bone inflammation of the intertrabecular spaces were seen, maximally at the insertion of the extensor and flexor tendons. The retained superficial fibrocartilaginous and tendinous cuff separated the inflamed extensor enthesis from the surrounding connective tissues. The thick proximal periosteum constituted a barrier between the inflamed bone and the matrical hypoderm. The lateral sections showed inflammation at 3 levels as follows: the enthesis of the interosseous ligament and collateral ligament, periosteum, and nail epithelium. In the 3 specimens, the inflammatory foci involving entheses and nails were prominent and never contiguous. This suggests that DIP PsA is not merely an extensor enthesitis and that the nail unit remains a microanatomical structure independent from the extensor enthesis, even with severe DIP PsA.
    MeSH term(s) Aged ; Arthritis, Psoriatic/diagnostic imaging ; Arthritis, Psoriatic/pathology ; Cadaver ; Finger Joint/diagnostic imaging ; Finger Joint/pathology ; Humans ; Male ; Nail Diseases/diagnostic imaging ; Nail Diseases/pathology ; Nails/diagnostic imaging ; Nails/pathology ; Psoriasis/diagnostic imaging ; Psoriasis/pathology ; Severity of Illness Index
    Language English
    Publishing date 2020-09-01
    Publishing country United States
    Document type Comparative Study ; Journal Article
    ZDB-ID 448469-1
    ISSN 1533-0311 ; 0193-1091
    ISSN (online) 1533-0311
    ISSN 0193-1091
    DOI 10.1097/DAD.0000000000001786
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Acquired (True) Leukonychia Punctate and Striata: Pathogenesis in the Light of Onychocytic Matricoma and Onychomatricoma.

    Perrin, Christophe

    The American Journal of dermatopathology

    2020  Volume 43, Issue 1, Page(s) 83–84

    MeSH term(s) Humans ; Nail Diseases ; Nails, Malformed
    Language English
    Publishing date 2020-08-07
    Publishing country United States
    Document type Journal Article ; Comment
    ZDB-ID 448469-1
    ISSN 1533-0311 ; 0193-1091
    ISSN (online) 1533-0311
    ISSN 0193-1091
    DOI 10.1097/DAD.0000000000001788
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: S-100 Protein Positivity in Onychomatricoma, a Potential Diagnostic Pitfall?

    Perrin, Christophe

    The American Journal of dermatopathology

    2020  Volume 42, Issue 8, Page(s) 622–623

    MeSH term(s) Humans ; Nail Diseases ; Nails ; Neoplasms ; S100 Proteins
    Chemical Substances S100 Proteins
    Language English
    Publishing date 2020-07-10
    Publishing country United States
    Document type Letter ; Comment
    ZDB-ID 448469-1
    ISSN 1533-0311 ; 0193-1091
    ISSN (online) 1533-0311
    ISSN 0193-1091
    DOI 10.1097/DAD.0000000000001624
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Concept of onychodermis has no microanatomical basis.

    Perrin, Christophe / Coutts, Michael

    Histopathology

    2023  Volume 84, Issue 4, Page(s) 707–708

    MeSH term(s) Humans ; Fibroblasts ; Immunohistochemistry ; Nails ; Skin Neoplasms
    Language English
    Publishing date 2023-11-15
    Publishing country England
    Document type Letter
    ZDB-ID 131914-0
    ISSN 1365-2559 ; 0309-0167
    ISSN (online) 1365-2559
    ISSN 0309-0167
    DOI 10.1111/his.15089
    Database MEDical Literature Analysis and Retrieval System OnLINE

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