Sweet syndrome (Introduction, Types, Pathophysiology)

 

Acute Febrile Neutrophilic Dermatosis (Sweet Syndrome)

Introduction

Sweet Syndrome (SS), ya acute febrile neutrophilic dermatosis, ko pehli baar Robert Douglas Sweet ne 1964 mein describe kiya tha. Ye ek reactive process hai jo achanak se tender, red-to-purple papules aur nodules ke saath hota hai, jo aksar plaques banate hain. Ye lesions zyadatar upper extremities, face, ya neck par hote hain. Is dermatologic condition ke saath fever aur elevated neutrophil levels (peripheral neutrophilia) bhi dekhe jaate hain.

Sweet syndrome ko teen types mein categorize kiya gaya hai based on underlying cause:

1. Classic ya Idiopathic Sweet Syndrome

Ye sabse common form hai, jo predominantly young women ko affect karta hai aur aksar mild respiratory illness ke baad hota hai. Iska association pregnancy, inflammatory bowel disease (IBD), vaccinations, inflammatory conditions, aur infections se bhi ho sakta hai.

2. Malignancy-Associated Sweet Syndrome

 Ye form underlying malignancy ke saath hota hai, kabhi-kabhi ye hidden cancer ka pehla indication hota hai. Ye paraneoplastic syndrome ya established cancer ka part bhi ho sakta hai, aur zyadatar acute myelogenous leukemia aur myelodysplastic syndrome ke saath linked hota hai.

3. Iatrogenic Sweet Syndrome

Ye variant kuch medications se triggered hota hai, sabse notably granulocyte colony-stimulating factor (G-CSF) se. Dusre implicated agents mein trimethoprim/sulfamethoxazole, minocycline, contraceptives jaise levonorgestrel/ethinyl estradiol, aur all-trans retinoic acid (ATRA) shamil hain. Antineoplastic agents, biologics, aur radiotherapy bhi iatrogenic Sweet syndrome se linked hain.

 

Pathophysiology of Sweet Syndrome

Sweet syndrome ek “neutrophil-mediated hypersensitivity reaction” hai jo infections, malignancies, drugs, ya inflammation ke triggers se hota hai. Iska hallmark hai abnormal activation of neutrophils, jo neutrophilia ke presence aur treatments targeting neutrophil function se support hota hai.

Granulocyte colony-stimulating factor (G-CSF key role play karta hai by prolonging neutrophil survival aur increasing unki activity. Elevated G-CSF levels disease severity se correlate karte hain, aur low neutrophil counts ke cases mein bhi lesions develop ho sakte hain due to elevated neutrophil function. All-trans retinoic acid (ATRA), jo acute promyelocytic leukemia mein use hoti hai, drug-induced cases mein neutrophil dysfunction se linked hai.

Cytokines, jaise IL-1, IL-2, aur IFN-γ, disease mein contribute karte hain, khaaskar malignancy-related forms mein. Elevated IL-6 levels disease activity se track karte hain aur corticosteroid treatment ke saath decrease ho jate hain.

Genetically, HLA-B54 (Japanese populations mein) aur chromosome 3q abnormalities is condition se associated hain. FLT3 mutations bhi Sweet syndrome-like skin disease se linked hain, aur familial cases suggest karte hain ek genetic predisposition ko.