Lymphangioma or lymphangiomatosis affect the skin, the covering of various organs and areas except of the brain. About 90% are diagnosed within the first two years of their existence[1,2
]. In adults, gastrointestinal tract involvement of mesenteric lymphangioma is very rare, the distal ileal mesentery is most frequently involved[3
]. The etiology of lymphangiomas is still unclear. They are considered to be a congenital dysplasia of lymphatic tissue and abnormal development of the lymphatic vessels during fetal life[5,6
]. The macroscopic appearance of lymphangioma is a cystic mass with partial septations and its histological characteristics are endothelial-lined, dilated, communicating lymphatic channels containing a variable amount of connective tissue and smooth muscle fiber[5,7
]. Lymphangiomas are generally classified as simple capillary, cavernous, and cystic according to the size of lymphatic space and the nature of the lymphatic wall[8,9
]. Cavernous lymphangioma is composed of dilated lymphatic vessels and lymphoid stroma and is connected with the adjacent normal lymphatics. Alternatively, cystic lymphangioma is composed of various-sized lymphatic spaces and has no connection with the adjacent normal lymphatics. However, as cystic lymphangiomas may have a cavernous area, clear differentiation between cystic and cavernous lymphangioma is not always possible[9,10
Most intra-abdominal lymphangiomas are of cystic form and generally appear as a thin-walled, mutiseptated, cystic mass with or without intracystic debris. Although these lymphangioma characteristics may appear in typical, mutiseptated, cystic masses on images including ultrasound and CT, some lymphangiomas may appear to be solid masses because they contain intracystic debris or hemorrhage or due to the microcystic nature of cavernous lymphangiomas. MRI is advantageous for detecting fluid-filled cystic lesions as it may reveal the cystic nature of cavernous lymphangiomas that appear as solid masses on CT[11
]. In our patient with rectal cancer, multiple nodular mesenteric masses infiltrating into the jejunum and adjacent mesentery were found. Because we did not suspect the microcystic nature of cavernous lymphangiomas, MRI was not performed to differentiate a microcystic tumor mimicking a solid mass.
As 18F-FDG is an analogue of glucose, its uptake within viable tumor cells is in proportion to the rate of glycolysis. Therefore, as 18F-FDG PET/CT can detect hypermetabolic tumor cells, it can be widely used for the detection, staging, and management of various malignant tumors[4
]. In our patient, as 18F-FDG PET/CT revealed no remarkable 18F-FDG uptake within the solid, mass-like lesions in the jejunal and adjacent mesentery, we were able to exclude the possibility of metastasis from the underlying rectal cancer.
The clinical symptoms of gastrointestinal and mesenteric lymphangiomas vary from being asymptomatic to acute abdominal symptoms such as obstruction or bleeding, according to the size and the localization of the tumor[10,12,13
]. The treatment of choice is complete surgical resection. Because lymphangioma is benign in nature, the prognosis is usually good despite the possibility of tumor recurrence. As Goh et al[14
] reported a 100% recurrence rate, complete lymphangioma resection is important in order to prevent tumor recurrence.
In conclusion, rarely occurring, cavernous mesenteric lymphangioma in adults occasionally appears on CT as a solid mass and it may be confused with metastasis in patients with malignancies. Therefore, 18F-FDG PET/CT may be helpful in excluding the presence of metastasis.