Fasciitis as a Complication of IgA Vasculitis

Immunoglobulin A vasculitis (IgAV) is a systemic small-vessel vasculitis caused by the deposition of IgA-based immune complexes, with myalgia being a rare complication. This study reports a pediatric case of IgAV with fasciitis. A five-year-old boy with no previous medical history was admitted to the hospital with abdominal pain and repeated bilious vomiting. Palpable purpura was observed on his face and right upper limb. Abdominal ultrasound and contrast-enhanced CT revealed decreased peristalsis and wall thickening of the fluid-filled duodenum, leading to a diagnosis of IgAV. Initial treatment with prednisolone and fasting improved his symptoms, but he complained of bilateral calf pain from day five with normal creatinine kinase levels. Fat-suppressed MRI on day 10 revealed high-signal areas around the soleus muscle, diagnosing fasciitis. Following steroid dose reduction, his myalgia worsened with difficulty falling asleep and the disability of standing up. Increasing the prednisolone dose alleviated his symptoms. The patient was discharged on day 23 without further myalgia. The pathogenesis of myalgia in IgAV remains unclear, but this case indicated a complication of fascial vasculitis and the effectiveness of steroid therapy. In conclusion, IgAV can be complicated by muscle involvement, and fasciitis should be considered a differential diagnosis of myalgia when creatinine kinase levels are normal. While supportive care is primary, steroid therapy should be considered depending on disease severity.


Introduction
Immunoglobulin A vasculitis (IgAV), formerly called Henoch-Schönlein purpura, is a systemic small-vessel vasculitis caused by the deposition of IgA-based immune complexes.It commonly affects the skin, joints, gastrointestinal tract, and kidneys [1].On the other hand, other organs, including the genitourinary, neurological, or pulmonary systems, have been reported [2].Myalgia is a rare complication whose pathogenesis is not well understood.Myalgia is not well recognized in contrast to arthritic symptoms, especially in pediatric patients, because their complaints of physical symptoms are ambiguous.On the other hand, some patients complain of myalgia without creatinine kinase (CK) elevation, and there are reports of fasciitis among them in Japan [3].Here, we report a pediatric case of IgAV with fasciitis.

Case Presentation
A five-year-old boy with no previous history was admitted to our hospital for abdominal pain and repeated bilious vomiting.A few petechial purpuras were scattered on the face and right upper limb.He was afebrile and normotensive.Abdominal ultrasound showed decreased peristalsis and wall thickening of the duodenum, which was filled with fluid.Contrasted-enhanced computed tomography also showed contrast mainly in the descending part of the duodenum (Figure 1A).Laboratory findings (Table 1) revealed a Creactive protein of 0.31 mg/dL (reference, <0.14 mg/dL), D-dimer of 3.3 µg/mL (<0.5 µg/mL), and factor XIII of 55.0% (<90%).Based on the European Alliance of Associations for Rheumatology (EULAR)/Pediatric Rheumatology International Trials Organisation (PRINTO)/Paediatric Rheumatology European Society (PRES) classification criteria, IgAV was diagnosed based on the palpable purpura (Figure 1B) and diffuse abdominal pain [1].After admission, the patient was treated with 1 mg/kg/day of prednisolone and fasting, and his gastrointestinal symptoms improved within a day.Oral intake was slowly resumed after day three.He began to complain of bilateral calf pain while standing on day five.There was no swelling, redness, heat, tenderness, or limited range of motion in the knee or ankle joints, but there was pain and tenderness in the muscles around the gastrocnemius.Muscle involvement was suspected, but CK was not elevated.The myalgia gradually worsened after a dose reduction of prednisolone to 0.5 mg/kg/day on day 8. Fatsuppressed magnetic resonance imaging (MRI) on day 10 revealed high-signal areas around the soleus muscle (Figures 1C, 1D).Thus, fasciitis in these regions was diagnosed.C-reactive protein and D-dimer had temporarily improved after the initiation of steroid therapy but increased again to 1.38 mg/dL and 1.1 µg/mL, respectively.These findings indicated a relapse of IgAV.The myalgia was managed with acetaminophen, but he had difficulty falling asleep and a disability standing up; therefore, the dose of prednisolone was increased again to 1 mg/kg/day.This dose change was remarkably effective.Considering the course of relapse and the decrease in factor XIII, 40 units/kg/day of factor XIII were administered three times from day 16.The dose of prednisolone was tapered gradually, without any trouble, from day 18.The patient was discharged from the hospital on day 23.After discharge, the patient did not complain of myalgia and was followed up for nephritis.

Discussion
Aside from the myalgia, the presence of palpable purpura, diffuse abdominal colicky pain, and the other clinical features of this case were typical of IgAV [1].In a retrospective multicenter survey of adults in France, the complication rate of myalgia was reported to be about 6% [2].There have been only seven reported cases of pediatric IgAV with myalgia [4][5][6][7][8].In these cases, myalgia is often attributed to intramuscular hemorrhage.Watanabe et al. suggested another pathologic mechanism, namely, muscle ischemia due to necrotizing inflammation affecting the small vessels within skeletal muscle [7].Fasciitis associated with IgAV, to date reported only in adult cases, has been attributed to leukocytoclastic vasculitis of intramuscular vessels [3].Our patient did not undergo a biopsy, and the pathological changes are not known.Myalgia was present in the lower extremities without an increase in CK in all reported cases.Our literature search found no other cases of fasciitis in pediatric IgAV.Thus, reports of complications between IgAV and fasciitis are limited.However, Takahashi et al. reported a case of fascial vasculitis detected by MRI as a characteristic finding in a patient with microscopic polyangiitis (MPA) presenting with myalgia [9].In this case of MPA, MRI showed high intensity around each muscular fascicle of the legs in the short T1 inversion recovery (STIR) image and the gadolinium-enhanced T1-weighted image.The pathological examination revealed necrotizing vasculitis localized in the deep fasciae and perimysium.Immunoglobulin A vasculitis also affects small vessels as well as MPA; thus, it can similarly cause necrotizing vasculitis in the fascia and show similar MRI findings.In summary, our patient was presumed to be affected by necrotizing vasculitis localized in the small vessels of fascia around the soleus muscle due to the deposition of IgA-based immune complexes.
Previous reports on pediatric IgAV have recommended supportive care for muscle involvement [8].Nonsteroidal anti-inflammatory drugs, such as acetaminophen, are important for pain management in addition to rest and exercise restrictions.Patients did not require additional treatment in those cases.In our case, however, supportive care alone was ineffective, and steroid therapy was necessary, with relapse occurring when the dose was reduced.As a result, the steroid dose had to be increased again.As in cases of gastrointestinal and joint involvement, steroid therapy was effective in reducing pain.

Conclusions
Immunoglobulin A vasculitis may be complicated by muscle involvement, and fasciitis should be considered a differential diagnosis of myalgia in the absence of CK changes.Although supportive care is the basic treatment, steroid therapy is effective in reducing symptoms.Therefore, the use of steroids should not be uniformly recommended because of the risk of side effects; it should be considered depending on disease severity.

FIGURE 1 :
FIGURE 1: A. Abdominal contrast-enhanced computed tomography showing contrast enhancement of the duodenum with fluid retention.B. Palpable purpura on the leg.C and D. Fat-suppressed (chemical shift selective saturation (CHESS)) magnetic resonance imaging of the lower thigh shows high-signal areas around the soleus muscle.