Lymphangioma of the Foot

Abstract

Ly JQ, Gilbert BC, Davis SW, Beall DP, Richardson RR 2-year-old girl who was known to have Turner’s syndrome presented to her primary care provider with an enlarging mass involving her left foot. Physical examination revealed that the left foot was diffusely enlarged but not discolored. Conventional radiography (Fig. 1A) showed a large infiltrating soft-tissue mass involving the entire plantar aspect of the foot, without identification of phleboliths or osseous abnormalities. Doppler sonography of the mass revealed no remarkable blood flow. MRI (Figs. 1B and 1C) revealed a predominantly nonenhancing soft-tissue mass containing variably sized cystic spaces showing low to intermediate T1 signal and high T2 signal. Interspersed fat was noted within the mass. No flow voids were identified. These findings indicated a vascular lymphatic malformation. The patient underwent surgical amputation of the left foot. The final histopathologic diagnosis was cystic lymphangioma (Fig. 1D). Soft-tissue lymphangiomas are relatively rare tumors that may involve almost any organ system. Approximately 90% of lymphangiomas are diagnosed in children younger than 2 years and lymphangiomas account for only 6% of benign childhood tumors. Although the specific origin is unclear [1], most experts consider lymphangiomas to be true congenital neoplasms resulting from erroneous embryogenesis [2]. Soft-tissue lymphangiomas most commonly occur in cervicofacial (up to 75%), axillary (up to 25%), or mediastinal (3–10%) areas. Patients usually present with a soft, fluctuant mass that has been progressively increasing in size. Rapid enlargement of the lesion may be seen when there is associated bleeding or infection. Histologically, lymphangiomas consist of ectatic lymphatic channels, occasionally containing a mild lymphocytic infiltrate. Classification by histologic appearance includes three subtypes: capillary, cavernous, and cystic [3]. The capillary form is composed of small thin-walled lymphatic vessels. Cavernous lymphangioma consists of large lymphatic channels with adventitial coats. The third and most common type, cystic lymphangioma or cystic hygroma, is composed of macroscopic lymphatic spaces. These lesions are often multiseptated, which is suggestive of infiltration across tissue planes. The different classifications of this lesion may represent various stages of disease [1]. In clinical practice, vascular malformations are classified as highflow or low-flow lesions. Those containing arterial components are considered high-flow lesions. Capillary, venous, and lymphatic malformations and their combinations are considered to be low-flow lesions. Radiography typically shows nonspecific findings. Sonography generally shows excellent through transmission because of the cystic nature of this process. Other sonographic findings may include multiple septations of varying thickness and fluid–fluid levels that represent layering of the hemorrhagic components of the lesion [4]. Sonography may help in differentiating a lymphangioma from a hemangioma, as there generally is no significant Doppler flow in a lymphangioma. CT findings are often nonspecific but can demonstrate the cystic nature of lymphangiomas. MRI is superior to other techniques for defining soft tissues and is useful for further characterization of the composition and extent of soft-tissue lymphangiomas. Lymphangiomas characteristically appear as heterogeneous, fluid-filled masses with low signal intensity (isointense to muscle) on T1-weighted images and show high signal intensity (greater than fat) on T2weighted images. These fluid-containing spaces correspond to the histologic findings of ectatic lymphatic channels. Additional findings may include fibrous septations seen as linear hypointensities on T2-weighted images, fluid–fluid levels representing hemorrhage, and aneurysmal dilatation of adjacent venous structures [5]. Neither cystic enhancement nor mild septal enhancement is seen in true lymphatic malformations. However, enhancement may be seen in mixed lymphatic–venous lesions. The differential diagnosis includes hemangioma and venous malformation. On MRI, lymphangiomas are characterized by the absence of feeding vessels and lack of intense contrast enhancement. Venous and lymphatic malformations may be difficult to differentiate on unenhanced MRI. After IV contrast administration, the lack of significant intralesional contrast enhancement is consistent with a lymphangioma. The lymphangioma in our patient’s foot showed characteristic MRI findings, allowing us to make an accurate preoperative diagnosis. Six percent of lymphangiomas spontaneously regress. The most widely accepted treat-