Subcutaneous granuloma annulare: radiologic appearance

Area of Science:

• Radiology
• Dermatology
• Pathology

Background:

• Granuloma annulare is a rare benign inflammatory skin condition.
• The subcutaneous form often presents as a superficial mass, frequently encountered in radiological practice.
• Limited literature exists on the imaging characteristics of subcutaneous granuloma annulare.

Purpose of the Study:

• To describe the radiologic appearance of subcutaneous granuloma annulare.
• To correlate imaging findings with histopathological characteristics.
• To aid in the diagnosis of this uncommon entity.

Main Methods:

• Retrospective review of radiologic images from five patients diagnosed with subcutaneous granuloma annulare.
• Inclusion of MRI (with gadolinium enhancement in three cases), radiographs, and bone scintigraphy.
• Analysis of lesion location, size, and signal characteristics on different imaging modalities.

Main Results:

• Radiographs revealed unmineralized nodular masses (1-4 cm) in the subcutaneous adipose tissue.
• MRI demonstrated masses with decreased signal intensity across pulse sequences and variable margins.
• Gadolinium-enhanced MRI showed extensive, diffuse enhancement.

Conclusions:

• Subcutaneous granuloma annulare characteristically presents as a nodular soft-tissue mass within the subcutaneous fat.
• MRI findings include decreased signal intensity and diffuse enhancement.
• Radiographs show soft-tissue masses without bone involvement, making this appearance highly suggestive in young patients.