Case Presentation: A 65 year old male with a history of mitral valve replacement, chronic obstructive pulmonary disease and chronic kidney disease presented with progressive skin lesions. He reported the onset of lesions, which he described as “small pimples”, on his hands approximately 4 weeks prior to presentation. They were initially limited to his hands but had rapidly progressed to involve more of his upper extremities and face. Over this same time interval, the lesions started expressing purulent and bloody fluid. He denied pain and itching. On physical exam, numerous violaceous erythematous papules and plaques with pseudovesiculation were noted on the dorsum of his hands. On his forehead, cheeks, and nose were dozens of pink indurated papules, some with overlying hemorrhagic crusting. Laboratory evaluation revealed a creatinine of 3.2 mg/dL. A review of his medical records indicated that his creatinine had been normal 1 year prior but had since been persistently elevated. Further laboratory evaluation revealed hematuria, proteinuria, normal complement levels and a positive test for anti-neutrophilic cytoplasmic antibody (ANCA)-PR3 antibody. A skin biopsy was performed which was consistent with histiocytoid Sweet Syndrome. The patient was started on high dose steroids and his rash slowly improved. No malignancy was identified following bone marrow biopsy and flow cytometry. A renal biopsy was subsequently performed and showed focally necrotizing/crescentic glomerulonephritis and tubulointerstitial inflammation with a granulomatous lesion consistent with acute on chronic progressive glomerulonephritis. A diagnosis of granulomatosis with polyangiitis (GPA) vasculitis was made and rituximab was added to the steroid treatment. Despite this treatment regimen his renal function continued to worsen. The patient had multiple complications during the admission, including mechanical valve failure with decompensated heart failure and volume overload, mental status changes and a cerebrovascular accident. The patient eventually opted for comfort-focused care only and passed away shortly thereafter.
Discussion: Histiocytoid Sweet syndrome (H-SS) is a variant of Sweet Syndrome that was first described in 2005. It is characterized by inflammatory infiltration of the dermis, primarily composed of histiocytoid mononuclear cells. Sweet syndrome, particularly the histiocytoid variant, is frequently associated with hematological malignancies, especially myelodysplastic syndrome but has also been associated with inflammatory states such as ANCA-positive vasculitides. Our patient presented with an acute onset of histiocytoid Sweet Syndrome in the setting of ANCA-positive glomerulonephritis. The pathogenesis of these disease entities are believed to both involve neutrophil or neutrophil progenitor dysfunction and therefore indicate possible shared dysregulatory mechanisms and a shared etiology.
Conclusions: This case demonstrates an unusual presentation of 2 rare diseases in the same patient, H-SS and GPA-vasculitis, requiring a multidisciplinary approach to diagnosis and treatment. When encountering such an unusual presentation it is important to thoroughly investigate all aspects of the case as the dual diagnosis in this patient demonstrates.