A 64-year-old male with a history of resected rectal cancer presented with a 1-week history of fever, chills, myalgias, generalized malaise, and 4-day history of a productive cough with yellow sputum and dyspnea. With the onset of his respiratory symptoms, he had an abrupt appearance of a skin rash on his hands and extremities. On examination, there were multiple violaceous pustular nodules on the dorsum of his hands (Image 1: Panel A) and extremities (Image 1: Panel B). Initial investigations revealed hemoglobin of 117 g/L, platelet count of 401 × 109/L, an elevated leukocyte count of 68 × 109/L with absolute neutrophil count of 60.2 × 109/L, and monocyte count of 5.4 × 109/L. Blood cultures were negative. A chest radiograph showed extensive bilateral patchy airspace opacities compatible with pneumonia (Image 1: Panel C). Skin biopsy revealed neutrophilic dermatosis. No viral inclusions were seen and the Gram stain and fungus stain (GMS) did not demonstrate any organisms. An erythrocyte sedimentation rate (ESR) was elevated at 92 mm/h. His pneumonia was treated and his leukocyte count decreased to 20 × 109/L with persistent skin lesions and monocytosis at discharge 11 days later. A subsequent bone marrow aspirate supported an underlying diagnosis of chronic myelomonocytic leukemia (CMML, Panel D) and normal male karyotype. Two months later, his skin lesions still persisted and only improved with a course of high-dose oral prednisone. The lesions resolved within a few days of starting prednisone and his CMML was managed supportively.
Sweet's syndrome, also called acute febrile neutrophilic dermatosis, presents typically with an abrupt onset of rapidly growing erythematous, painful papules, nodules, or plaques over the head, neck, arms, and legs . Additionally, vesicles or bullae may appear on top of these lesions . Skin biopsy will show papillary and mid-dermal infiltration of neutrophils. This condition is associated with respiratory infections, malignancies, and certain medications. Acute myeloid leukemia has been commonly associated with this conditions but it has been reported with other myeloid malignancies such as myelodysplastic syndrome and CMML rarely .
In this patient, Sweet's syndrome may be associated with his pneumonia but most likely was due to his underlying CMML as the association with respiratory infections occur mainly in children . This case highlights the importance of searching for an underlying cause such as a hematologic malignancy even in the presence of an active infection.