Patient presented with sudden painful erythematous lesions on the face and neck and was urgently referred to dermatology after initial clinical evaluation. Recent medication was discontinued due to suspected drug-related reaction.

Workup included skin biopsy, complete blood count, and testing for antibodies, lupus anticoagulant, and serological markers. Oral corticosteroids were started for symptom control.

Within 48 hours, lesions improved significantly and pain subsided. Laboratory results showed leukocytosis with neutrophilia, positive antibodies and lupus anticoagulant, while routine serology remained negative.

Skin biopsy findings obtained later confirmed the diagnosis of Sweet syndrome.

Sweet syndrome, also known as acute febrile neutrophilic dermatosis, is a rare inflammatory condition characterized by dense neutrophilic infiltration in the skin and sudden onset of painful erythematous papules or plaques.

Its exact cause is unclear, but it is believed to involve cytokine-driven neutrophil activation. It is considered an immune-mediated hypersensitivity reaction associated with infections, malignancies, or drug exposure.

Drug-induced cases are relatively common and may be linked to medications such as antibiotics, antiepileptics, contraceptives, antihypertensives, vaccines, and colony-stimulating factors. First-line treatment is oral corticosteroids, often producing rapid clinical improvement.

Differential diagnosis includes urticaria, contact dermatitis, toxicoderma, and cutaneous lupus. Definitive diagnosis requires correlation of clinical presentation, laboratory findings, and histopathology to exclude systemic disease and guide appropriate therapy.