This clinical case involves a 55-year-old woman with a history of high blood pressure and chronic obstructive pulmonary disease (COPD), highlighting a rare dermatological condition with systemic implications that should be considered in primary care. The patient had no known allergies, smoked around ten cigarettes daily, and had been on enalapril for six years and inhaled formoterol for two years.
Due to a worsening of her respiratory condition, her pulmonologist adjusted her treatment by stopping formoterol and prescribing inhaled capsules containing indacaterol and glycopyrronium. Just two days after starting this new inhalation therapy, she visited her primary care clinic with complaints of painful red patches on her cheeks and neck, accompanied by a low-grade fever. She denied any recent use of new cosmetics or changes in diet and reported some sun exposure, though she claimed to have used adequate protection. She had no symptoms of a recent cold or upper respiratory infection. Concerned by the sudden appearance of these skin lesions, her primary care provider made an urgent referral to dermatology.
The dermatology team recommended discontinuing the new medication and proceeded with a skin biopsy and blood work, including a full blood count, antibody screening, lupus anticoagulant testing, and serology. Oral corticosteroids were prescribed to address the symptoms. Within 24 to 48 hours, the intensity of the lesions began to subside and the pain decreased. The blood tests showed leukocytosis with a marked increase in neutrophils, while antibody panels, lupus anticoagulant, and serology were all negative. Approximately twenty days later, the results from the skin biopsy confirmed the diagnosis of Sweet syndrome, also known as acute febrile neutrophilic dermatosis. This rare inflammatory condition falls within the category of neutrophilic dermatoses and is characterized histologically by an accumulation of neutrophils in the dermis.
Clinically, Sweet syndrome typically presents with the sudden onset of painful, erythematous papules or plaques, often appearing asymmetrically on the face, neck, upper chest, and hands. These skin manifestations are commonly associated with systemic symptoms such as fever and leukocytosis. Although the exact cause of Sweet syndrome remains unknown, research suggests it may result from an immune-mediated response involving cytokines that stimulate neutrophil and histiocyte activity. Often, a hypersensitivity reaction is triggered by a prior event such as an upper respiratory tract infection, underlying malignancy, autoimmune disease, or drug exposure. While drug-induced cases and idiopathic presentations are more common in women, Sweet syndrome can also serve as a warning sign for serious systemic diseases, including hematologic cancers.
Various medications have been linked to Sweet syndrome, with the most common being contraceptives, antiepileptics, antibiotics, antihypertensives, colony-stimulating factors, and vaccines. However, this case is particularly notable because the suspected trigger was an inhaled therapy—specifically a combination of indacaterol and glycopyrronium—a combination not previously reported in the literature as being associated with Sweet syndrome. The first-line treatment for this condition is oral corticosteroids, which typically produce rapid improvement in both systemic symptoms and skin lesions, often within days. When a patient presents with erythematous papular eruptions on the face and neck, differential diagnoses should include urticaria, contact dermatitis, drug-induced skin reactions, and cutaneous lupus. In this case, these possibilities were carefully ruled out through the patient’s history, clinical examination, and supporting lab results. Once the biopsy confirmed Sweet syndrome, a full systemic workup was necessary to exclude any underlying diseases. Although rare, Sweet syndrome should always be considered in the differential diagnosis of acute dermatologic conditions, especially when lesions coincide with recent medication changes. It’s important to remember that Sweet syndrome doesn’t just affect the skin—it may also involve internal organs and act as a marker for infections, inflammatory bowel diseases, autoimmune disorders, or even cancers. Therefore, once the diagnosis is confirmed, further evaluation is critical to investigate any potential underlying systemic conditions. Primary care providers should remain alert to rare conditions like this, as early recognition and appropriate referral can significantly improve patient outcomes. Even when a precise diagnosis cannot be established in the primary care setting, knowledge of rare diseases enables timely management. This case also emphasizes the need for awareness regarding drug-induced reactions, even involving medications not previously linked to such adverse effects, broadening our understanding of possible triggers and enhancing diagnostic accuracy in clinical practice.
