Lymphadenopathy at the medial epitrochlear region in cat-scratch disease.

Our objective was to describe the imaging features of lymphadenopathy at the medial epitrochlear region as frequently seen in cat-scratch disease (CSD) and to compare these features with those seen in non-CSD. Ten patients (four males and six females) presented with a subcutaneous soft tissue mass at the medial epitrochlear region. Three patients were younger than 15 years. Magnetic resonance imaging was performed in all patients. All lesions turned out to be regional lymphadenopathy instead of soft tissue neoplasm. They were caused by benign disorders in eight cases, including seven CSD and one other infection, and in two cases by metastatic disease. All lesions, except for three benign ones, were solitary. On MRI, high signal intensity (SI) strands in the surrounding soft tissue on T2-weighted images (WI) were present in all cases. Three cases of CSD showed homogeneous SI on both T1- and T2WI. After contrast administration, a moderate, homogeneous enhancement was seen. The other seven lesions, except for one metastasis, had both solid and liquid components. Liquid components showed high SI on T2WI without enhancement, whereas solid components had intermediate SI on T2WI and marked enhancement after contrast administration. Pathological findings in seven patients, including four with CSD, supported the tentative diagnosis made on MRI. One of two patients with CSD had positive serological test. Cat-scratch disease is a major cause of a soft tissue swelling at the medial epitrochlear region. Identification of lymphadenopathy and its presentation on MRI may be helpful in eliciting an animal-scratch history and achieving diagnostic and therapeutic aims in patients without primary cancer.