Histiocytoid Sweet Syndrome in a Child without Underlying Systemic Disease

Abstract

Sweet syndrome (acute, febrile, neutrophilic dermatosis) is characterized by the acute onset of an eruption of painful nodules or erythematous or violaceous plaques on the limbs, face and neck. These symptoms are accompanied by fever. The diagnostic features include histopathological findings of dermal neutrophilic infiltration without leukocytoclastic vasculitis or peripheral blood leukocytosis. Sweet syndrome is associated with infection, malignancies, autoimmune disease, pregnancy, and drugs. Patients with Sweet syndrome demonstrate a complete and rapid response to systemic steroid administration. Recently, a distinct variant of Sweet syndrome was reported, termed “histiocytoid Sweet syndrome”, in which the infiltration of myeloperoxidase-positive histiocytoid mononuclear cells are observed (in contrast to the infiltration of neutrophils). The other clinical features are similar to those of classic Sweet syndrome. Pediatric Sweet syndrome is uncommon, and the histiocytoid type is even rarer. To date, four cases of histiocytoid Sweet syndrome have been reported in children. Herein, we describe a case of histiocytoid Sweet syndrome in an otherwise healthy 10-year-old boy with no underlying systemic disease in whom non-steroidal, anti-inflammatory drug treatment was successful.

The blister that got out of hand

“…Sweet syndrome (SS), or acute febrile neutrophilic dermatosis, is characterized by the acute onset of painful nodules or violaceous erythematous plaques accompanied by fever, leucocytosis and neutrophilia 1 . SS can be idiopathic, drug‐induced or follow a viral infection, particularly of the upper respiratory tract.…”

Infantile histiocytoid Sweet syndrome without an underlying systemic association

“…6 Pediatric HSS is a histopathologic variant that is even more uncommon, with only 5 previous cases documented and all infantile cases having an identifiable underlying systemic association. 2,[7][8][9] A diagnosis of Sweet syndrome requires both major criteria and at least 2 minor criteria. 10 The major criteria are as follows: (1) abrupt onset of painful and well-demarcated erythematous or violaceous papules or nodules and (2) dermis with neutrophilic infiltration without leukocytoclastic vasculitis.…”

“…1 The entity is characterized clinically by an abrupt cutaneous eruption of painful erythematous nodules and plaques accompanied by fever and leukocytosis. 2 On histopathologic examination, prominent papillary dermal edema and a dense dermal infiltrate of neutrophils are classic. 3 In 2005, Requena et al 4 described a variant termed ''histiocytoid Sweet syndrome'' (HSS).…”

“…HSS, although clinically indistinguishable from its classic counterpart, demonstrates an inflammatory infiltrate composed of myeloperoxidase (MPO)-positive immature mononuclear cells with a histiocytoid morphology rather than neutrophils. 2,4,5 These immature mononuclear cells simulate histiocytes both in appearance and with CD68 staining. 2,5 Therefore, MPO staining is necessary to confirm that these cells are neutrophil precursors and not true histiocytes.…”

“…2,4,5 These immature mononuclear cells simulate histiocytes both in appearance and with CD68 staining. 2,5 Therefore, MPO staining is necessary to confirm that these cells are neutrophil precursors and not true histiocytes. 5 Sweet syndrome has been associated with underlying systemic diseases of infectious, inflammatory, autoimmune, and neoplastic nature.…”