Abstract
INTRODUCTION: Henoch-Schönlein Purpura, another name for IgA vasculitis, is the most common kind of systemic vasculitis in children. Palpable purpura, arthralgia, stomach pain, and renal involvement are typically its defining features. A thorough examination is necessary since severe or uncommon presentations may mimic other systemic inflammatory or neoplastic disorders, most cases resolve on their own. Here, we report an adolescent boy who had severe and atypical HSP, which included gastrointestinal inflammation, renal proteinuria, severe weight loss, and laboratory abnormalities such thrombocytosis, hypoalbuminemia, and elevated D-dimer.The example highlights how challenging it is to diagnose atypical vasculitis and how crucial interdisciplinary treatment is. CASE DESCRIPTION: A previously well adolescent male presented with a persistent non-blanching rash on the lower limbs around the Easter time, alongside abdominal pain, reduced appetite, weight loss. By late May, he developed acute left leg pain and calf tenderness; a markedly elevated D-dimer (>12,000) prompted exclusion of thromboembolic disease, though Doppler was normal. Bloods revealed thrombocytosis (platelets 881), hypoalbuminaemia (14 g/L), normal renal function, and negative autoimmune screening. He was readmitted in early June due to worsening rash, weight loss and systemic symptoms. CT angiogram of the chest, abdomen, and pelvis showed distal jejunal/proximal ileal enteritis with reactive mesenteric nodes but no vascular abnormalities. A hypodense liver lesion was noted, felt to represent fatty infiltration. Skin biopsy confirmed IgA vasculitis. The patient received IV methylprednisolone (30 mg/kg for 3 days), followed by high-dose oral prednisolone. Faecal calprotectin was markedly raised (3760), and renal involvement was evident with elevated urine P:Cr (max 250). He was managed with careful nutritional support due to biochemical signs of refeeding risk (low phosphate, low T3). His condition improved steadily with resolution of rash, improved appetite, and weight gain. Plans were made for immunosuppressive maintenance with azathioprine (TPMT was normal) due to systemic involvement. He continues under outpatient review with monitoring of renal function, LFTs, and inflammatory markers. DISCUSSION: A severe and unusual course of HSP, which is typically thought to be benign and self-limiting, is demonstrated in this instance. Despite the prevalence of gastrointestinal and cutaneous symptoms, this patient’s combination of weight loss, hypoalbuminemia, significantly elevated inflammatory markers, and extended systemic involvement led to the possibility of other diagnoses, such as polyarteritis nodosa, IBD, or cancer. Significantly increased D-dimer and thrombocytosis added to the diagnostic difficulty and heightened the possibility of thromboembolic events or systemic inflammatory reactions. A skin sample that revealed IgA deposition, which is consistent with IgA vasculitis, finally validated the diagnosis. Although intestinal involvement in HSP typically resolves on its own, in this instance, enteritis and elevated fecal calprotectin indicated severe mucosal inflammation, which raised concerns about nutritional impairment and refeeding risk. Although renal function remained steady, proteinuria was indicative of renal involvement. Although continued monitoring was recommended, the renal team decided against biopsy at this point because of improving clinical and biochemical trends. Cardiac pathology and vascular occlusion were excluded by radiology and echocardiography. In order to manage problems like refeeding syndrome and guide immunosuppression, this case emphasizes the importance of early MDT engagement, involving rheumatology, nephrology, gastrointestinal, dermatology, and dietetics. In order to lower the chance of recurrence and enable safe steroid tapering, the patient was started on azathioprine after steroid induction due to the degree of systemic involvement. KEY LEARNING POINTS: • Atypical HSP may present with significant systemic involvement, including GI enteritis, hypoalbuminaemia, and renal proteinuria, necessitating broad differential work-up. • Marked thrombocytosis and elevated D-dimer can occur in vasculitis but require careful exclusion of thrombosis, sepsis, or malignancy. • Refeeding syndrome should be considered in patients with significant weight loss and biochemical derangements, especially in those with gastrointestinal involvement and restricted intake. • Multidisciplinary input is essential in complex paediatric vasculitis to guide diagnosis, monitor organ involvement, and plan immunosuppression. Escalation beyond steroids may be necessary for severe or systemic HSP. Because of the gut, kidney, and skin involvement, azathioprine was started for this patient in order to reduce the chance of relapse and facilitate steroid weaning. This example serves as a reminder that even “common” illnesses like HSP can manifest in severe and uncommon ways, necessitating multidisciplinary care and thorough evaluation.