Four year old boy with anterior mediastinal mass. Has been coughing for two weeks.
Very low FDG uptake of an anterior mediastinal mass (5.6 X 4 X 8 cm; SUV max 0.8) on attenuation corrected images. The majority of the lesion is hypoactive on non attenuation corrected images.
Axial low dose CT demonstrates an heterogenous mass with fluid (mean HU 15-20) and tissue (mean HU 30-40) components.
Non-specific infracarinal isolated lymph node (SUV max 1.9).
Mediastinal cystic lymphangioma
Lymphangioma are rare benign congenital malformations characterized by an increased number of dilated lymphatic channels. They are classified in three categories: simple (capillary), cavernous or cystic (hygroma). Simple lymphangiomas are composed of thin-walled lymphatic channels and present themselves as small cutaneous lesions. Cavernous lymphangiomas consist of thin-walled lymphatics channel with associated stroma. Cystic lymphangiomas are large, well-defined multicystic spaces lined by endothelium with connective tissue component.
Cystic lymphangiomas are most common and the majority are detected before the age of two. The most common locations are neck and axilla. The majority of mediastinal lymphangiomas are extension of neck lesion. Isolated mediastinal is uncommon, accounting for approximately 1% of lymphangiomas. Most of the time, mediastinal lymphangiomas are located in the anterior compartment. They are usually asymptomatic but can cause pain, cough and dyspnea.
The most common characteristics of cystic lymphangioma are well-capsulated, smoothly marginated lesions with homogeneous low attenuation. Higher attenuation may occur in lesions with a combination of fluid and solid tissue.
Few authors report the metabolic behavior of lymphangioma. Like the present case, no significant metabolic activity is described in several studies. However, there are reports of FDG-avid lymphangiomas. Dong et al. suggested that lymphocytes in the fibrous septa may have contributed to FDG uptake in a retroperitoneal cystic lymphangioma.
Complete surgical resection is the treatment of choice, but may be difficult. Incomplete resection can result in recurrence.
Ghedira et al : Isolated mediastinal cystic lymphangioma in children: About two cases. Respiratory Medicine CME (2008) 1, 270-273
Jeung et al : Imaging of cystic masses of the mediastinum. Radiographics. 2002 Oct;22 Spec No:S79-93. Review.
Faul et al : Thoracic lymphangiomas, lymphangiectasis, lymphangiomatosis, and lymphatic dysplasia syndrome. Am J Respir Crit Care Med. 2000 Mar;161(3 Pt 1):1037-46. Review
Dong et al F-18 FDG uptake in a retroperitoneal cystic lymphangioma mimicking malignancy. Clin Nucl Med. 2012 Jun;37(6):e154-6