Lysosomal-associated membrane protein-2 plays an important role in the pathogenesis of primary cutaneous vasculitis.

OBJECTIVES: Recent research suggests that lysosomal-associated membrane protein-2 (LAMP-2) could be one of the target antigens in the pathogenesis of vasculitides. We established a transgenic rat model, env-pX rats, with various vasculitides including cutaneous vasculitis. Human primary cutaneous vasculitis includes cutaneous polyarteritis nodosa (CPN) and Henoch-Schönlein purpura (HSP). We measured serum anti-LAMP-2 antibody levels in morbid env-pX rats and injected anti-LAMP-2 antibody into premorbid env-pX rats. We further measured serum anti-LAMP-2 antibody levels in patients with CPN and HSP. METHODS: Cutaneous vasculitis was observed in ∼30% of 6-month-old morbid env-pX rats. In contrast, these findings were rare in premorbid env-pX rats under 3 months old. We also examined 85 patients with CPN and 36 adult patients with HSP. Serum anti-LAMP-2 antibody levels were determined using ELISA. Premorbid env-pX rats under 3 months old were given an i.v. injection of anti-LAMP-2 antibody at day 0 and day 7. At day 14, these rats underwent histopathological and direct immunofluorescence examination. Cell surface LAMP-2 expression of rat neutrophils was examined by flow cytometry. RESULTS: Serum anti-LAMP-2 antibody levels were significantly higher in morbid env-pX rats than in wild-type normal rats. In addition, the levels in the cutaneous vasculitis group of morbid env-pX rats were significantly higher than the no cutaneous vasculitis group. Intravenous anti-LAMP-2 antibody injection into premorbid env-pX rats under 3 months old induced infiltration of neutrophils into cutaneous small vessels. Anti-LAMP-2 antibody-binding neutrophils were detected there. LAMP-2 expression on the cell surface of neutrophils in premorbid env-pX rats under PMA stimulation was higher compared with controls. Serum anti-LAMP-2 antibody levels in CPN and HSP were significantly higher than those of healthy controls. CONCLUSION: These data support a positive relationship between anti-LAMP-2 antibody and cutaneous vasculitis.

Serum anti-lysosomal-associated membrane protein-2 antibody levels in cutaneous polyarteritis nodosa.

Lysosomal-associated membrane protein-2 (LAMP-2) is a target antigen for anti-neutrophil cytoplasmic antibodies (ANCAs), which are closely linked to a subset of primary systemic vasculitides. Cutaneous polyarteritis nodosa (CPN) is a necrotizing vasculitis of small to medium-sized arteries within the skin. We measured levels of serum anti-LAMP-2 antibody in 50 patients with CPN, 8 with microscopic polyangiitis (MPA), and 34 healthy persons. We also investigated the presence of ANCA in patients with CPN using indirect immunofluorescence (IIF), a direct ELISA and a capture ELISA specific for myeloperoxidase (MPO) and proteinase 3 (PR3). Serum anti-LAMP-2 antibody levels differed significantly between patients with CPN (0.263 U/ml) and those with MPA (0.180 U/ml) (p = 0.0102). Serum of all patients with CPN was negative for MPO-ANCA and PR3-ANCA by both direct ELISA and capture ELISA. In contrast, IIF assay revealed ANCA in 42 (84.0%) of the 50 CPN patients. Serum anti-LAMP-2 antibody levels in the perinuclear ANCA (P-ANCA) group were significantly elevated compared with the non-ANCA group (p = 0.0147). We suggest that anti-LAMP-2 antibody could play an important role in the pathogenesis of CPN in the presence of P-ANCA detected by IIF.

A novel deletion mutation of mouse ruby-eye 2 named ru2(d)/Hps5(ru2-d) inhibits melanocyte differentiation and its impaired differentiation is rescued by L-tyrosine.

In our laboratory, a single autosomal recessive mutation in a phenotype similar to ruby-eye (ru/Hps6(ru)) or ruby-eye 2 (ru2/Hps5(ru2)) spontaneously occurred in siblings of C57BL/10JHir (+/+, black) mice in 2006. RT-PCR analysis revealed that this novel mutation, named ru2(d)/Hps5(ru2-d), exhibited frameshift by 997G deletion in the Hps5 gene. To clarify the mechanism of the hypopigmentation, the characteristics of proliferation and differentiation of ru2(d)/ru2(d) epidermal melanoblasts and melanocytes cultured in a serum-free medium were investigated. The proliferation of ru2(d)/ru2(d) melanoblasts and melanocytes did not differ from that of +/+ melanoblasts and melanocytes. However, the differentiation of ru2(d)/ru2(d) melanocytes was greatly inhibited. Tyrosinase (TYR) activity, expression of TYR, TYR-related protein 1 (TRP1) and TRP2 (dopachrome tautomerase, DCT), eumelanin synthesis, and the number of stage IV melanosomes markedly decreased in ru2(d)/ru2(d) melanocytes. However, excess L-tyrosine (Tyr) added to culture media from initiation of the primary culture rescued the reduced differentiation through increase in TYR activity, expression of TYR, TRP1, TRP2 and Kit, eumelanin synthesis, and stage IV melanosomes. L-Tyr injected into ru2(d)/ru2(d) mice also stimulated melanocyte differentiation. These results suggest that the ru2(d) allele inhibits melanocyte differentiation, and that its impaired differentiation is rescued by excess Tyr.

Use of warfarin therapy at a target international normalized ratio of 3.0 for cutaneous polyarteritis nodosa.

BACKGROUND: Cutaneous polyarteritis nodosa (CPN) is an uncommon disorder that can be difficult to manage effectively. We have previously suggested that CPN might be associated with the presence of anti-phosphatidylserine-prothrombin complex (anti-PS/PT) antibodies, members of the antiphospholipid antibody family. OBJECTIVE: To evaluate clinical manifestations and effective treatments of CPN. METHODS: We conducted a retrospective analysis of three patients with CPN who responded to warfarin therapy. IgG and IgM anti-PS/PT antibodies were measured with a specific enzyme-linked immunosorbent assay. RESULTS: There was a dramatic improvement in our three CPN patients following warfarin therapy adjusted to a target international normalized ratio (INR) of about 3.0. Active disease progression was halted by sustained warfarin therapy during which the patients experienced resolution of their skin manifestations. LIMITATIONS: A small number of cases were studied and the study design was retrospective. CONCLUSION: We propose that warfarin therapy at a target INR of roughly 3.0 could be effective for treating patients with CPN. We further believe that treatment with warfarin led to the effective attenuation of anti-PS/PT antibodies related to prothrombin, and improved the symptoms in our CPN patients.

IgM in lesional skin of adults with Henoch-Schönlein purpura is an indication of renal involvement.

BACKGROUND: Henoch-Schönlein purpura (HSP) is a multisystem disease believed to be a consequence of the entrapment of circulating IgA-containing immune complexes in blood vessel walls throughout the skin, kidneys, and gastrointestinal tract. The skin manifestations are characterized by nonthrombocytopenic palpable purpura over the lower extremities. OBJECTIVE: We assessed adult patients with HSP who had nonthrombocytopenic palpable purpura on the extensor surfaces of their lower limbs, and had no associated connective tissue disease. Patient medical records, including clinical presentation, laboratory data, and direct immunofluorescence (DIF) reports, were reviewed retrospectively. METHODS: We reviewed the records of 25 adult patients with HSP who presented at our department, between 2006 and 2008, with an initial cutaneous manifestation of palpable purpura on their lower extremities. Adult HSP was defined in all cases as documented leukocytoclastic vasculitis according to a skin biopsy specimen, with histopathologic evidence of IgA deposition by DIF. Statistical analyses were performed using a χ(2) test to compare prevalence among each clinical manifestation. RESULTS: There was a significant correlation between IgM deposition by DIF and renal involvement (χ(2) = 5.23, P = .022). IgM deposition and complement 3 deposition by DIF showed a close relationship (χ(2) = 5.11, P = .024). There was a significant positive correlation between serum IgA and C-reactive protein levels (Spearman's rank correlation coefficient = 0.35, P = .044). LIMITATIONS: These findings should be validated in larger studies. Renal biopsies were not done to confirm the presence of nephritis. CONCLUSIONS: This study suggests that IgM deposition in palpable purpura based on DIF provides an indicator of nephritis in adult patients with HSP. We believe that IgM deposition could be related to the pathogenic factors that trigger the development of renal involvement.

Differences in anti-phosphatidylserine-prothrombin complex antibodies and cutaneous vasculitis between regular livedo reticularis and livedo racemosa.

OBJECTIVES: We examined the prevalence of LAC, aCL antibodies (Abs), anti-beta(2)-glycoprotein I (anti-beta(2)GPI) Abs and anti-phosphatidylserine-prothrombin complex (anti-PS/PT) Abs in patients with regular livedo reticularis or with livedo racemosa to determine whether those Abs correlate with the clinical or serological features. Assuming that a correlation exists, early recognition of the serological features of the cutaneous manifestations may aid in the treatment and prediction of complications. METHODS: We examined the prevalence of LAC, aCL Abs, anti-beta(2)GPI Abs and anti-PS/PT Abs in 143 Japanese patients who presented at our department with regular livedo reticularis or livedo racemosa between 2003 and 2008. LAC was determined according to the guidelines recommended by the Subcommittee on Lupus Anticoagulant/Phospholipid-Dependent Antibodies. Levels of anti-PS/PT, aCL and anti-beta(2)GPI Abs in serum samples taken from patients were measured by specific ELISAs. RESULTS: Anti-PS/PT Abs were detected in 94 (65.7%) of the livedo patients. Further, IgM anti-PS/PT Abs were detected in 90 (62.9%) of the livedo patients. Serum IgM anti-PS/PT Ab levels were significantly higher in livedo racemosa patients compared with regular livedo reticularis (19.2 +/- 17.0 vs 8.93 +/- 8.48 U/ml, P = 0.0013). Cutaneous vasculitis was significantly more prevalent among patients with livedo racemosa compared with regular livedo reticularis (P = 0.0014). Livedo racemosa patients had significantly higher CRP serum levels than regular livedo reticularis patients. Livedo racemosa has a stronger association with skin ulceration and arthralgia compared with regular livedo reticularis. Overall, we found a statistically significant association between cutaneous vasculitis and ischaemic cerebrovascular events in our livedo patients. CONCLUSIONS: We speculate that IgM anti-PS/PT Abs could be implicated in disease susceptibility for livedo racemosa. We further suspect that cutaneous vasculitis could be closely related to pathogenic factors that trigger the development of livedo racemosa. Early detection of cutaneous vasculitis in skin biopsies of livedo patients should be useful for prognostic evaluation, including ischaemic cerebrovascular events.

Granuloma annulare-like skin lesions as an initial manifestation in a Japanese patient with adult T-cell leukemia/lymphoma.

Granuloma annulare is characterized by noncaseating dermal granulomas with connective tissue changes. A relationship with hematologic and solid malignancies has been suggested in some cases. We describe a 70-year-old man who had erythematous annular plaques on his elbows, upper extremities, and wrists for a period of 3 months. Histologic examination revealed epithelioid cell granulomas associated with dense atypical lymphocytes in the dermis. Immunohistochemical staining of skin specimens showed a prominent infiltration of CD3+, CD4+, CD5+, and CD25+ cells. Human T-cell leukemia virus type I proviral DNA was detected in the blood and cerebrospinal fluid by Southern blot analysis and polymerase chain reaction assay. The patient was given the diagnosis of adult T-cell leukemia/lymphoma based on the initial cutaneous manifestations. His condition progressed rapidly and led to his death. The granuloma annulare-like skin lesions in our patient could be considered as a peculiar immunologic hypersensitivity reaction of the host against the tumor cells or persistent human T-cell leukemia virus type I viral antigens. Dermatologists should be aware that this skin condition may be an initial manifestation of adult T-cell leukemia/lymphoma.

Drug-induced hypersensitivity syndrome: drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome induced by aspirin treatment of Kawasaki disease.

Drug-induced hypersensitivity syndrome (DIHS), also known as drug reaction with eosinophilia and systemic symptoms (DRESS), is a severe multiple-organ condition caused by drug treatment. The current report describes a Japanese boy who underwent aspirin treatment for Kawasaki disease, and who subsequently presented with the manifestations of DIHS/DRESS syndrome. He had been treated with a single high dose of intravenous immunoglobulin and aspirin orally for Kawasaki disease. One month after the onset of Kawasaki disease, he developed a generalized maculopapular eruption, high-grade fever, leukocytosis with eosinophilia, and an increased number of atypical lymphocytes, severe liver dysfunction, lymphadenopathy, and prominent increases in antihuman herpesvirus-6 immunoglobulin G titer. The activity of 2',5'-oligoadenylate synthetase was elevated at the onset stage. Hypersensitivity to aspirin was confirmed by skin patch test and by lymphocyte stimulation test. Based on these findings, the patient was diagnosed with DIHS/DRESS caused by aspirin. To our knowledge, there have been no previous reports of aspirin-induced hypersensitivity syndrome subsequent to Kawasaki disease. The activity of 2',5'-oligoadenylate synthetase might be useful as a diagnostic marker of DIHS/DRESS syndrome and for exploring its pathogenesis.

Sudden elevation of plasma D-dimer levels induced by the combination therapy of dabrafenib and trametinib: Report of two cases.

The combination therapy of dabrafenib and trametinib revolutionized the treatment for BRAF V600-mutated melanoma. Various adverse events have been reported for this treatment, most notably fever. Herein, we report two cases of novel an adverse event, namely sudden and significant elevation of plasma D-dimer level induced by this therapy. In the first case, the remarkable elevation of plasma D-dimer level up to 87.4 mg/dL was noted on day 11, and in the second case, the plasma D-dimer level reached 125.5 mg/dL on day 25. In both cases, D-dimer levels gradually decreased after the cessation of this therapy. Although the exact cause is not clear, we assume two possible hypotheses: the first is that the combination therapy may induce disseminated intravascular coagulation, and the second is that the therapy induced pathological condition of secondary thrombotic microangiopathies. Our cases suggest that this thrombotic adverse event should not be overlooked, and coagulation parameters need to be monitored during the course of this treatment.

Proteomic analysis of immature murine melanocytes at different stages of maturation: a crucial role for calreticulin.

BACKGROUND: We have established two immature melanocyte cell lines from murine neural crest cells. NCC-E3 cells have Stage II melanosomes and express tyrosinase while in NCCmelb4 cells, the melanosomes remain at Stage I and tyrosinase is not expressed. These cell lines may be useful in studying the differentiation of melanocyte precursors. OBJECTIVE: To perform proteomic analysis of the two cell lines to identify proteins related to and possibly responsible for their different maturation stages. METHODS: Western blotting, two-dimensional differential image gel electrophoresis (2D-DIGE), liquid chromatography-tandem mass spectrometry (LC-MS/MS), real-time PCR analysis and RNA interference using siRNA were employed in this study. RESULTS: Western blotting revealed that the processed form of gp100, which is specific for Stage II melanosomes, is expressed in NCC-E3 cells but not in NCCmelb4 cells. 2D-DIGE identified two protein spots showing 4.06- and 2.22-fold increases in NCC-E3 cells compared to NCCmelb4 cells. Analysis of those proteins by LC-MS/MS revealed that the former was calreticulin and the latter was BiP/GRP78. When calreticulin mRNA expression in NCC-E3 cells was blocked by siRNA, tyrosinase protein was abolished and DOPA-reactivity was decreased, although tyrosinase mRNA was abundantly expressed after the same treatment. CONCLUSION: Calreticulin, a lectin chaperone, is an essential molecule for the processing of tyrosinase in murine melanocytes. The role of molecular chaperones such as calreticulin should be considered when analyzing the mechanism(s) of melanocyte differentiation.

Melanocyte precursors express elastin binding protein and elastin-derived peptide (VGVAPG) stimulates their melanogenesis and dendrite formation.

BACKGROUND: In congenital or acquired dermal melanocytosis, attachment of melanocyte with elastic fiber was shown in electron microscopy of unknown biological meaning. We hypothesize elastin-derived peptide may play a role in activating dermal melanocyte precursors. OBJECTIVES: This study was designed to determine: (i) whether melanocyte precursors express elastin binding protein (EBP); (ii) ontogenic expression of EBP and elastin in murine embryonic skin; (iii) the effects of elastin-derived peptide (VGVAPG) on melanocyte precursors. METHODS: Using immunohistochemistry or Western blot to identify EBP on murine embryonic sections, neural crest cell (NCC) primary culture explants, or two melanocyte precursor cell lines, NCCmelb4 and NCCmelan5. NCC explants or cells were treated with VGVAPG to compare its effect on proliferation, dendrite formation, melanosome maturation and tyrosinase mRNA expression of melanocyte precursors. RESULTS: EBP was immunostained on c-kit+ melanocyte precursors. 67kDa EBP protein was immunoblotted on NCCmelb4 and NCCmelan5 cells. EBP was expressed early at embryonic day (E) 9.5, but elastin appeared later at E12.5 skin. VGVAPG increased DOPA-positive cell number and enhanced their dendrite formation in NCC explants. Electron microscopy showed advanced melanosome maturation in NCC explants or cells treated with VGVAPG. VGVAPG enhanced tyrosinase mRNA expression in NCCmelan5 cells. CONCLUSIONS: Melanocyte precursors expressed EBP. VGVAPG stimulated their melanogenesis and dendrite formation. In the developmental journey interaction between elastin and EBP-expressed melanocyte precursors in embryos happened mainly since the stage of tertiary melanoblasts. These findings first provide biological evidences for the interaction between melanocyte and elastic fiber.

Transforming growth factor-beta overexpression in cutaneous extramedullary hematopoiesis of a patient with myelodysplastic syndrome associated with myelofibrosis.

Extramedullary hematopoiesis (EMH) is a relatively rare, but well-documented, manifestation of chronic myeloproliferative disorders. Microscopically, foci of EMH consist of erythroid and myeloid precursors intermixed with megakaryocytes. It typically occurs in the spleen and liver, but very occasionally manifests as cutaneous EMH. We report a 76-year-old Japanese man with cutaneous EMH arising from myelodysplastic syndrome associated with myelofibrosis. His cutaneous manifestations showed multiple skin-colored firm nodules over the head, trunk, and extremities. We detected high plasma levels of transforming growth factor (TGF)-beta1 in our patient. Immunohistochemical analysis of the skin biopsy sample revealed TGF-beta1 overexpression in immature hematopoietic cells and dermal fibroblasts within the cutaneous EMH mass of the dermis. These findings suggest that TGF-beta could play some role in the onset of cutaneous EMH. Five months after his first visit to our dermatologic clinic, the patient developed bone-marrow failure and died. Based on our observations, accelerated malignancy in the bone marrow should be considered in any patient with cutaneous EMH. It is presumed that TGF-beta released from hematopoietic cells within the cutaneous EMH play a critical role in the activation of hematologic malignancy.

Approach for the Derivation of Melanocytes from Induced Pluripotent Stem Cells.

Induced pluripotent stem (iPS) cells have the ability to differentiate into multiple cell types in the body and have an unlimited growth potential. However, iPS cell-derived melanocytes produced by existing protocols have significant limitations in developing novel strategies for regenerative medicine and cell therapies of pigmentation disorders in humans because they involve culture in media containing fetal bovine serum and nonphysiological agents. In this study, we established an in vitro approach to generate iPS cell-derived human melanocytes that have higher proliferation rates and increased melanin production compared with melanocytes prepared by previously reported approaches. Importantly, our iPS cell-derived human melanocytes are prepared in fetal bovine serum-free culture conditions that do not contain any nonphysiological agents. We designed two original methods, transferring black colonies by pipette and recovering black cell pellets from centrifuged medium, and numerous human iPS cell-derived melanocytes proliferated in gelatinous dishes coated with Matrigel after 12 days. We also succeeded in inducing melanin pigmentation in the nude mouse skin in vivo using those human iPS cell-derived melanocytes. We propose that this method using iPS cells established from T cells in the blood of normal human volunteers could be applied clinically to develop regenerative medicine and cell therapies for various forms of human pigmentation disorders.

Excess tyrosine rescues the reduced activity of proliferation and differentiation of cultured recessive yellow melanocytes derived from neonatal mouse epidermis.

The murine recessive yellow (Mc1r(e)) is a loss-of-function mutation in the receptor for alpha-melanocyte-stimulating hormone, melanocortin receptor 1 (Mc1r) and produces yellow coats by inducing pheomelanin synthesis in hair follicular melanocytes. However, it is not known whether the Mc1r(e) mutation affects the proliferation and differentiation of melanocytes. In this study, the proliferation and differentiation of recessive yellow epidermal melanocytes cultured in dibutyryl cyclic AMP-supplemented serum-free medium were investigated in detail. The melanocytes produced mainly eumelanin in this culture system. The proliferation of recessive yellow melanocytes was decreased compared with that of wild-type at the e-locus, black melanocytes. The differentiation of melanocytes was also delayed and inhibited in recessive yellow mice. Tyrosinase (TYR) activity and TYR-related protein 1 (TRP1) and TRP2 (dopachrome tautomerase, DCT) expressions were decreased and, in addition, the maturation of stage IV melanosomes was inhibited. Excess l-tyrosine (l-Tyr) added to the culture media rescued the reduced activity of proliferation of melanocytes. l-Tyr also stimulated TYR activity and TRP1 and TRP2 expressions as well as the maturation of stage IV melanosomes and pigmentation. These results suggest that the Mc1r(e) mutation affects the proliferation and differentiation of melanocytes and l-Tyr rescues the reduced proliferative and differentiative activities by stimulating TYR activity and TRP1 and TRP2 expressions as well as melanosome maturation.

Sphingosine 1-phosphate accelerates wound healing in diabetic mice.

BACKGROUND: Blood platelets store sphingosine 1-phosphate (S1P) abundantly and release this bioactive lipid extracellularly. S1P acts as an intercellular mediator through interaction with the endothelial differentiation gene (EDG)/S1P family of G protein-coupled receptors. Of the EDG family S1P receptors, EDG-5 (S1P2) is inhibited in migration induced by S1P. Diabetes impairs numerous aspects of tissue repair. Failure of wound angiogenesis is known to delay diabetic wound healing. OBJECTIVES: We examined whether S1P subcutaneous injection could improve the healing of full-thickness skin wounds in healthy and diabetic mice. We further determine if the combined S1P and EDG-5 (S1P2) antagonist injection in diabetic mice could affect wound healing. Finally, we examined the histopathological findings of the wound following S1P injection in diabetic mice. METHODS: Eight- to 10-week-old BALA/c mice, diabetic db/db mice and Wister rats were used for the studies. A full-thickness wound was made on the dorsal skin of the healthy and diabetic mice. Either 10 microM or 100 microM of S1P or vehicle control (BSA/PBS) was injected into the wound bed every day. We calculated the wound area after each injection. EDG-5 (S1P2) antagonist (JTE-013) or vehicle (DMSO) was then injected in addition to the S1P around the dorsal wound of diabetic mice and the wound diameter was measured. Wound tissue samples were excised following injection for histopathological examination. RESULTS: Wound area in normal BALA/c mice did not significantly decrease upon S1P injection compared to S1P-untreated controls. S1P injection alone showed significant promotion of wound healing in diabetic mice compared to no S1P treatment. The combination of S1P and EDG-5 (S1P2) receptor antagonist administration induced maximal wound healing in diabetic mice. Histopathological examination revealed that S1P induces neo-vascularization potential in rats and diabetic mice wound. CONCLUSIONS: S1P injection in diabetic mice significantly accelerated cutaneous wound healing in the neo-vascularization process. The results demonstrate that S1P affects and sustains all key cellular processes responsible for wound repair and point to a unique potential for this molecule in the therapy of diabetic wounds, particularly as an angiogenic agent in treatment of diabetic wounds.

Clinical and histopathologic features of 8 patients with microscopic polyangiitis including two with a slowly progressive clinical course.

BACKGROUND: Microscopic polyangiitis (MPA) is a systemic antineutrophil cytoplasmic autoantibody-associated vasculitis associated with necrotizing and crescentic glomerulonephritis and pulmonary capillaritis. MPA generally has a rapidly progressive clinical course, but there have been recent reports of slowly progressive cases. OBJECTIVE: To evaluate the typical cutaneous findings of MPA, we recorded the clinical and histopathologic features of the cutaneous manifestations. METHODS: Eight patients with MPA, who had presented with cutaneous manifestations between 2001 and 2005 in our department, were retrospectively reviewed. They had necrotizing vasculitis in their cutaneous lesions as confirmed by skin biopsy specimens. Patients with other known connective tissue diseases were not included in the study. RESULTS: All 8 patients with MPA presented cutaneously with erythematous macules on their extremities. Livedo reticularis (5/8, 68%) was also observed. Six of the 8 patients with MPA were given the diagnosis within 3 months of their initial manifestation. In skin biopsy specimens, necrotizing vasculitis was noted in the reticular dermis to the subcutaneous fat. In contrast, the other two patients with MPA were given the diagnosis about 10 years after their initial manifestation. Histopathologic findings demonstrated necrotizing vasculitis with moderate neutrophilic infiltrations in the papillary to middle dermis in the latter two patients. Serum myeloperoxidase-antineutrophil cytoplasmic autoantibody levels were only moderlately elevated in the latter two patients and they were given the diagnosis of slowly progressive MPA. Histopathologically, palisading granulomas were present on the elbow of one of them. LIMITATIONS: The study was based on histopathological analysis in a limited number of patients due to the rareness of the investigated disease. CONCLUSIONS: There appears to be a correlation between a slowly progressive clinical course of MPA and the depth of dermal involvement and the severity of neutrophilic infiltration in biopsy specimens. Based on these results, we believe that these characteristic patterns may help clinicians establish an earlier diagnosis of possible MPA with positive antineutrophil cytoplasmic autoantibody titers.