Early skeletal muscle manifestations in polyarteritis nodosa and ANCA-associated vasculitis.

Skeletal muscle involvement is common in patients with small- and medium-sized vasculitis, particularly polyarteritis nodosa (PAN) and antineutrophil cytoplasmic antibody-associated vasculitis (AAV). Despite being not included in the standard classification criteria for PAN and AAV, skeletal muscle involvement is an important clinical indicator, particularly when vasculitic myopathy is the only pathological evidence in the absence of other organ involvement. Herein, we comprehensively reviewed and compared the clinical features of 71 and 135 patients with PAN and AAV, respectively, with skeletal muscle involvement at the time of disease onset. Most patients with PAN and AAV exhibited skeletal muscle involvement, often characterized by myalgia and occasional muscular weakness, predominantly in the lower extremities. Myalgia and weakness were observed more frequently in the distal lower extremities in patients with PAN than in those with AAV. In contrast, skeletal muscle involvement tended to exhibit a more dispersed distribution across all four extremities in those with AAV. Muscle magnetic resonance imaging T2-weighted and short-tau inversion recovery sequences can effectively identify hyperintense areas attributed to hypervascularity of affected muscle tissues and serve as a sensitive and useful modality for visually determining the suitable biopsy site. >90% of patients with PAN and AAV demonstrated perivascular inflammation in their affected muscle tissues, whereas fibrinoid necrosis of the vessel walls was reported in two-thirds of patients. Serum creatine kinase (CK) levels were within the normal range in approximately 80% of patients presenting with skeletal muscle involvement in PAN and AAV. Furthermore, muscle fiber damage was milder in patients with skeletal muscle involvement in PAN and AAV than those with idiopathic inflammatory myositis. Meanwhile, serum CK levels were elevated in 65-85% of patients with PAN and AAV who had myofiber necrosis and degeneration in the affected muscles. Most patients with PAN and AAV showed improvement in skeletal muscle involvement following glucocorticoids (GCs) administration; however, relapse was observed in some patients during the tapering of GCs. In summary, skeletal muscle involvement is a potential indicator for establishing PAN and AAV diagnoses during the early phases of the disease.

Painless Panniculitis upon the Treatment of Clinically Amyopathic Dermatomyositis with Anti-MDA5 Antibody.

Panniculitis, a rare cutaneous manifestation in patients with dermatomyositis (DM), usually presents as a painful erythematous lesion. We herein report a 32-year-old woman with panniculitis that appeared as an indurated plaque without pain or redness after a 4-month episode of clinically amyopathic DM during treatment with prednisolone and tacrolimus. She experienced no pain; however, the firmness and extent gradually worsened. Based on our findings, including the histopathological results, DM panniculitis was diagnosed. Azathioprine was additionally administered, leading to remission. DM panniculitis can develop as a painless induration during immunosuppressive treatment, and azathioprine may be a useful treatment.

Clinical characteristics of patients with myalgia as the initial manifestation of small and medium-sized vasculitis: a retrospective study.

Myalgia is a common symptom in small and medium-sized systemic vasculitis, sometimes occurring as the initial or only clinical manifestation of vasculitis. This study investigated the clinical features and diagnostic process in patients presenting with myalgia as the initial symptom of anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) or polyarteritis nodosa (PAN). We included 93 patients diagnosed with AAV or PAN by retrospectively reviewing their clinical records at the initial diagnosis. Clinical findings and diagnostic methods were assessed in patients with myalgia. Of 93 patients, myalgia was observed in 21 (22.6%) patients, with diagnostic classifications of microscopic polyangiitis (MPA) in 12 (52.4%), granulomatosis with polyangiitis in 2 (9.5%), eosinophilic granulomatosis with polyangiitis in 2 (9.5%), and PAN in 5 (23.8%). Myalgia was present in the lower extremities of all patients; more than 80% of patients had pain in the calf muscle. In 10 patients with myalgia, including 7 with MPA and 3 with PAN, muscle biopsy was performed because myalgia was the main symptom and no other impaired organs were suitable for biopsy. Consequently, 8 patients had necrotizing vasculitis, leading to MPA or PAN diagnosis, although muscle pathology was not evaluated in patients without myalgia. Muscle magnetic resonance imaging was useful in determining the biopsy site. Myalgia, especially in the lower limbs, may be an initial clinical sign of vasculitis, particularly in MPA or PAN patients. Moreover, the histological evidence of muscular vasculitis can contribute to a definite diagnosis especially in patients presenting with myalgia as an early symptom of AAV or PAN.

Macrophage activation syndrome in adult dermatomyositis: a case-based review.

Macrophage activation syndrome (MAS) is a severe and life-threatening syndrome associated with autoimmune diseases, characterized by fever, hepatosplenomegaly, and pancytopenia. Dermatomyositis (DM) is one of the causes of MAS; however, its clinical characteristics in DM patients remain unclear. This study aimed to present a case of anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive DM complicated by MAS in a 29-year-old woman and to review the literatures including similar cases. Even though symptoms and cytopenia of our patient were refractory to combination therapy, including glucocorticoids, immunosuppressants, and plasma exchange, the administration of rituximab (RTX) resulted in rapid clinical improvement and glucocorticoid reduction. The literature review revealed 18 adult patients with DM associated MAS. Most patients developed MAS within 3 months from DM onset. A monotherapy of glucocorticoid was insufficient to control the disease, and the mortality of MAS in DM was higher than that of MAS in other rheumatic diseases, despite being treated by various means. RTX may be an effective treatment for patients with DM complicated by MAS who are refractory to conventional therapy. Anti-MDA5 antibody could influence the development of MAS; however, further investigations are needed to elucidate the association between myositis-specific antibody and MAS.

Characteristics of Circulating Natural Killer Cells and Their Interferon-γ Production in Active Adult-onset Still Disease.

OBJECTIVE: To investigate the characteristics of circulating natural killer (NK) cells and their interferon (IFN)-γ-producing ability in adult-onset Still disease (AOSD). METHODS: Peripheral blood mononuclear cells were obtained from 22 patients in the acute phase of AOSD (acute AOSD); 7 of the 22 patients after treatment (remission AOSD), and 11 healthy controls (HC). NK cells and their IFN-γ expression levels were analyzed by flow cytometry. Additionally, the cytokine receptors of interleukin (IL)-12, IL-15, and IL-18 on NK cells were also evaluated. RESULTS: The frequency of NK cells was significantly lower in acute AOSD than in HC. NK cell counts significantly increased in remission AOSD. Expression of IL-12 and IL-15 receptors on NK cells was significantly increased in acute AOSD, whereas that of IL-18 receptor indicated no significant difference among 3 groups. IFN-γ expression in NK cells was significantly higher in acute AOSD than in HC, and significantly decreased in remission AOSD. The absolute number of NK cells and IFN-γ-expressing NK cells revealed an inverse correlation with serum ferritin levels in acute AOSD. In 2 distinct subsets of NK cells, CD56dim NK cells significantly exhibited higher IFN-γ expression than CD56bright NK cells in acute AOSD. CONCLUSION: In acute AOSD, NK cells displayed lower proportion, whereas they had higher ability for IFN-γ production than in HC; moreover, upregulation of IL-12 and IL-15 receptors on NK cells may promote IFN-γ production. In addition, disease activity may be implicated in regulating the number of NK cells and IFN-γ-expressing NK cells in AOSD.

Hypertrophic Pachymeningitis as an Early Manifestation of Relapsing Polychondritis: Case Report and Review of the Literature.

Neurological involvement in relapsing polychondritis (RP) is relatively rare. We describe the case of an 80-year-old man who presented with hypertrophic pachymeningitis (HP) together with arthritis as the first manifestation of RP. Auricular chondritis, which subsequently determined the diagnosis of RP, occurred a few weeks after the detection of HP. The neurological symptoms, as well as arthritis, were promptly improved by treatment with corticosteroids. It is generally difficult to diagnose RP in the absence of typical cartilaginous involvement; however, the present case suggests that HP may occur as an early clinical manifestation of RP.