Ankylosing spondylitis and Sweet's syndrome

Insights Into the Pathogenesis of Sweet's Syndrome

Sweet's syndrome, also known as Acute Febrile Neutrophilic Dermatosis, is a rare inflammatory condition. It is considered to be the prototype disease of neutrophilic dermatoses, and presents with acute onset dermal neutrophilic lesions, leukocytosis, and pyrexia. Several variants have been described both clinically and histopathologically. Classifications include classic Sweet's syndrome, malignancy associated, and drug induced. The cellular and molecular mechanisms involved in Sweet's syndrome have been difficult to elucidate due to the large variety of conditions leading to a common clinical presentation. The exact pathogenesis of Sweet's syndrome is unclear; however, new discoveries have shed light on the role of inflammatory signaling, disease induction, and relationship with malignancy. These findings include an improved understanding of inflammasome activation, malignant transformation into dermal infiltrating neutrophils, and genetic contributions. Continued investigations into effective treatments and targeted therapy will benefit patients and improve our molecular understanding of inflammatory diseases, including Sweet's syndrome.

Ankylosing spondylitis associated with Sweet's syndrome: a case report

INTRODUCTION

Sweet's syndrome is an acute neutrophilic dermatosis characterized by a diffuse dermal infiltrate of mature neutrophils. In most cases, it occurs as an isolated phenomenon (idiopathic Sweet's syndrome) but it can be drug induced or associated with a variety of underlying diseases such as infections, neoplasms, and chronic inflammatory diseases. The association between Sweet's syndrome and ankylosing spondylitis is rare. Only a few cases have been reported in the literature. We report a new case in which we describe an outbreak of acute neutrophilic dermatosis revealing ankylosing spondylitis.

CASE PRESENTATION

A 33-year-old Moroccan man presented with large-joint polyarthralgia, inflammatory pain in his buttocks and lower lumbar spine, fever and skin lesions. On examination, the patient had a low-grade fever, six tender but not swollen joints, limitation of motion of the lumbar spine, and painful erythematous maculopapules over his face, neck, and hands. Laboratory tests showed hyperleukocytosis, and elevated erythrocyte sedimentation rate and C-reactive protein. The immunological tests and infectious disease markers were negative. Investigations for an underlying neoplastic disease remained negative. Magnetic resonance imaging showed a bilateral sacroiliitis. Skin biopsy findings were consistent with Sweet's syndrome. The diagnosis of Sweet's syndrome associated with ankylosing spondylitis was established. Nonsteroid anti-inflammatory drugs were started and the patient showed rapid clinical and biological improvement.

CONCLUSION

Three observations of the association between Sweet's syndrome and spondylarthropathy have been reported in the literature. The cause of this association remains unclear. Some hypotheses have been developed, but further studies are needed to confirm or refute them.