Drug-associated histiocytoid Sweet?s syndrome: a true neutrophilic maturation arrest variant

A Mysterious Rash Following Cardiothoracic Surgery: A Not So Sweet Ending

A male in his 70s, with a recent history of aortic valve replacement, mitral valve repair, and permanent pacemaker implantation (PPM), developed a fever, raised inflammatory markers, and a disseminated rash. Despite being attributed a diagnosis of an unspecified connective tissue disorder and erythema nodosum at his local hospital, his symptoms continued to deteriorate. A subsequent urgent admission was arranged to his original cardiothoracic centre for the exclusion of infective endocarditis (IE). Although this was subsequently ruled out by echocardiography and microbiological evaluation, a diagnosis of Sweet syndrome (SS) was made following a punch biopsy of a skin lesion. This was later attributed to myelodysplastic syndrome following a bone marrow biopsy. In this report, we firstly describe our diagnostic algorithm for reaching this diagnosis and the characteristic skin lesions associated with this condition. We furthermore review the history of SS, its known associations, and treatment options.

Myelodysplasia Cutis

CONTEXT.—

Myelodysplasia cutis is an emerging concept in cutaneous neoplasia. Many of these cases were previously included under the umbrella of histiocytoid Sweet syndrome. However, with the advent of next-generation sequencing, cutaneous involvement by myelodysplastic syndrome is being increasingly recognized.

OBJECTIVE.—

To review histiocytoid Sweet syndrome and myelodysplasia cutis and discuss our current understanding of these entities. Additionally, to discuss how next-generation sequencing can be applied in the evaluation of cutaneous infiltrates of immature histiocytoid cells.

DATA SOURCES.—

The English-language literature from 2005 to 2023 on the topic of histiocytoid Sweet syndrome and myelodysplasia cutis was reviewed.

CONCLUSIONS.—

Biopsy specimens showing infiltrates of histiocytoid, immature myeloid cells may represent cutaneous involvement by myelodysplastic syndrome. Close clinical correlation is recommended in these cases. Recent studies suggest that next-generation sequencing is useful in separating myelodysplasia cutis from true histiocytoid Sweet syndrome. This distinction has important implications for patients.

Neoplastic or inflammatory? A case report of Sweet syndrome with CD30+ cells in a patient with B-lymphoblastic leukemia

CD30+ cells are typically part of lymphoproliferative disorders but can also be seen in inflammatory dermatoses. We present a case of 47-year-old man with a history of B-lymphoblastic leukemia (B-ALL) who presented with fever, leukocytosis, and papulonodular skin lesions, involving the extremities and trunk. A punch biopsy specimen demonstrated papillary dermal edema with a neutrophilic and histiocytic infiltrate extending into the subcutis. The infiltrate also harbored scattered large cells that were positive for CD30 and demonstrated the immunohistochemical profile of monocytes. A diagnosis of histiocytoid Sweet syndrome with CD30+ cells was made. The case is unique, demonstrating a combination of Sweet syndrome variants with subcutis involvement, histiocytoid morphology, and large CD30+ cells. A prior history of B-ALL and immunohistochemical profile of monocytes with immature morphology broadened the differential diagnosis and added to the diagnostic challenge.

Subcutaneous histiocytoid sweet syndrome associated with crohn disease in an adolescent

We report a case of subcutaneous histiocytoid Sweet syndrome in an adolescent with Crohn disease. A 14-year-old boy with a 1-year history of ileocolonic and perianal Crohn disease, treated with infliximab and azathioprine, was admitted to the Pediatrics Department with malaise, abdominal pain, bloody diarrhea, and fever (39°C) from 15 days ago. Two days later, he developed cutaneous lesions consisting of tender, erythematous, and violaceous papules and nodules scattered over his legs, soles, and upper extremities. Laboratory studies revealed neutrophilia, microcytic anemia, and elevation of both erythrocyte sedimentation rate and C-reactive protein rate. A skin biopsy specimen showed deep dermal and predominantly septal inflammatory infiltrate in the subcutaneous tissue composed of polymorphonuclears, eosinophils, and mononuclear cells of histiocytic appearance. These histiocytoid cells stained positive for myeloperoxidase. Subcutaneous Sweet syndrome is a rare subtype of acute neutrophilic dermatosis, in which the infiltrate is exclusively or predominantly located in the subcutaneous tissue, causing lobular or septal panniculitis. It is often described in patients with an underlying haematological disorder or caused by drugs, but very rare in patients with inflammatory bowel disease, especially in childhood or adolescence. To our knowledge, this is the first case of subcutaneous histiocytoid type in a paediatric patient.