Rare Case of Lymphangioma

Case History: 2-year-old female present with complaints of swelling of vulva, gluteal region, and left thigh since birth which gradually increased in size. No evidence of discoloration of skin or varicosity is seen and non-tender.

Diagnosis: Congenital vascular malformation, lymphangioma of upper thigh and vulva.

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Figure 1. External appearance of child showing hypertrophy of left thigh and vulva. No e/o of skin discoloration or varicosity is noted.

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Figure 2. X-ray left thigh (AP view) showing increased soft tissue shadow involving left thigh, however bones and joint undervesion appear normal. No e/o lytic and sclerotic lesion is noted.

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Figure 3. Ultrasonography of local part showing fluid filled nonvascular cystic areas within the subcutaneous plane, no evidence of muscular involvement is noted.

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Figure 4. Coronal T2WI of hip and both thighs showing increased signal intensity in soft tissue involving subcutaneous tissue of left thigh, gluteal region, both inguinal regions, and vulva. Bones and muscle show normal signal intensity.

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Figure 5. Coronal T1FS postcontrast images showing heterogenous enhancement of internal septas, no evidence of pooling of blood in subcutaneous cystic spaces is noted.

Radiograph Observations: A large soft tissue shadow is noted in the left thigh and perineal region. No evidence of calcification is seen. Bones and joint under vision appears normal.

Contrast MRI of Both Thighs Observations: Large altered signal intensity (hyperintense on T2WI, STIR, and PD FS images, hypointense on T1WI). Soft tissue lesion in labia majora, labia minora, subcutaneous plane of perineal region, both inguinal regions, lower part of anterolateral abdominal wall, anterolateral part of left gluteal region, and whole circumference of left thigh up to the knee.

The lesion shows heterogenous postcontrast enhancement of internal septas. No e/o pooling of contrast in the above mentioned soft tissue lesions is noted. Underlying muscles and bones show normal signal intensity. S/o congenital vascular malformation possibly lymphangioma.

Discussion
Soft-tissue lymphangiomas are relatively rare tumors that may involve almost any organ system. Approximately 90% of lymphangiomas are diagnosed in children younger than age 2 and lymphangiomas account for only 6% of benign childhood tumors. Although the specific origin is unclear, most experts consider lymphangiomas to be true congenital neoplasms resulting from erroneous embryogenesis. 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 progressively increased 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. 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. In clinical practice, vascular malformations are classified as high-flow 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. 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 T2-weighted 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. Neither cystic enhancement nor mild septal enhancement is seen in true lymphatic malformations. However, enhancement may be seen in mixed lymphatic-venous lesions.

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