Granuloma annulare on ultrasound: a diagnosis to consider in pediatric skin lesions.

BACKGROUND: Granuloma annulare (GA) is a rare, benign, inflammatory, self-limited, granulomatous dermatosis that affects children and young adults. The most frequent clinical form is localized GA. Deep GA generally presents as painless palpable subcutaneous nodules in the lower extremities, buttocks, hands and scalp. They may have a fast-growing firm subcutaneous mass presentation, mimicking a malignant lesion which requires an imaging evaluation. Diagnosis of deep GA can be more difficult and imaging evaluation is frequently performed, ultrasound being one of the techniques used. OBJECTIVE: To describe the US characteristics of GA in a pediatric series. MATERIALS AND METHOD: Descriptive, retrospective, 14-year study of all pediatrics GA cases. RESULTS: Twelve pediatric cases with GA. 66% females. The lesions were mainly distributed in the extremities: 50% in the lower extremities and 42% in the upper extremities, mostly with multiple lesions. A total of 45 lesions were analyzed, 8 superficial lesions and 37 deep lesions. On ultrasound, the superficial GA corresponded to hypoechoic poorly defined solid plaque like or nodular lesions, located in the dermal-epidermal plane. The deep GA presented as solid nodular, poorly defined hypoechoic lesions that compromised the deep subcutaneous-aponeurotic plane. CONCLUSION: GA is an inflammatory lesion that presents as a superficial or deep palpable nodule that predominantly affects children. Superficial and deep GA present characteristic findings on US that can guide the diagnosis. The radiologist needs to know its US appearance to be able to suggest the diagnosis, especially in multiples lesions.

"Truffle sign". A suspicious malignant pattern of lymphadenopathies in children observed on ultrasound. Preliminary study.

BACKGROUND: The differential diagnosis of lymphadenopathies in children including benign and malignant conditions is often difficult to identify by ultrasound (US). The lymphadenopathies in children are frequent and mostly benign, therefore it is essential to decide what patients should undergo further studies. OBJECTIVE: To describe the potential usefulness of a new suspicious ultrasound sign on pediatric lymphadenopathies that can orient the diagnosis of malignancy. MATERIALS AND METHODS: We retrospectively reviewed all pediatric cases with lymphadenopathy suspicious of lymphoma or lymphoproliferative syndrome on soft tissue ultrasound from 2014 to 2021. Two expert ultrasound radiologists reviewed ultrasound images of these patients, associating the internal structure of infiltrated adenopathy with the internal structure of the truffles. RESULTS: On ultrasound, twelve cases presented enlarged lymphadenopathy with loss of internal structure, without hilum; mostly hypoechoic parenchyma, with some fine echogenic serpiginous linear surrounding hypoechoic pseudo nodular images, resembling the inner structure of black truffles. This US pattern looked suspicious and histological study was recommended. In 9 cases a lymphomatous infiltrated adenopathy was confirmed on biopsy. CONCLUSION: The truffle sign is a new potential suspicious ultrasound sign, that can suggest malignant lymphadenopathy in children. This ultrasound pattern can have some probable usefulness to the radiologist in order to recommend further studies, including histological study, that need to be validated by a larger sample. It is important to recognize easily and early the lymphomatous compromise in a lymph node.