Intraabdominal cystic lymphangiomas obscured by marked superimposed reactive changes: clinicopathological analysis of a series.

Cystic (or cavernous) lymphangiomas are uncommon tumors that most often occur in the head and neck, axilla, or groin of young children but are detected occasionally in adulthood at various other anatomic sites. When arising in the abdomen, cystic lymphangiomas may present with acute abdominal pain. We have encountered examples of mesenteric and retroperitoneal cystic lymphangiomas associated with such marked superimposed reactive and inflammatory changes that their lymphatic nature is obscured, a situation that is not widely recognized. To further characterize these lesions, 7 abdominal lymphangiomas associated with florid reactive changes were retrieved from the authors' consultation files. There were 5 female patients and 2 male patients (median age, 42 years; range, 1 month to 51 years). Five cases presented in adulthood. Tumor size ranged from 8 to 20 cm (median, 15 cm). Three tumors arose in the mesentery of the small intestine and 4 arose in the retroperitoneum (one of which also involved the posterior mediastinum). Three patients presented with a short history of abdominal pain. Radiological studies revealed large cystic or solid masses; clinical differential diagnoses included sarcoma (2 cases), enteric duplication cyst (2 cases), and cystic tumor not otherwise specified. Grossly, the tumors were generally multiloculated cystic masses associated with areas of fat necrosis and hemorrhage. The cysts often contained thick, gelatinous, or milky fluid. Histologically, all cases showed extensive areas of granulation tissue, most also including a floridly cellular reactive myofibroblastic proliferation, obscuring the lymphatic nature of the lesion. Two cases contained extensive areas of xanthogranulomatous inflammation. In foci where the underlying lesion could be discerned, the tumors were composed of cystically dilated lymphatic spaces, some of which were partially invested by a layer of smooth muscle and were associated with occasional lymphoid aggregates. The lymphatic spaces contained either clear fluid or large numbers of foamy macrophages. The lymphatic endothelial cells lining the cystic spaces were generally attenuated with no cytological atypia. One case showed features of a complex vascular malformation with a predominant component of cavernous lymphangioma. By immunohistochemistry, in all cases, the endothelial cells lining the dilated lymphatic spaces were positive for CD31 and D2-40, 4 of 7 were positive for CD34, and all were negative for keratin. Clinical follow-up information was available for 4 patients (median, 26 months; range, 22-36 months): 3 patients had no evidence of recurrence and 1 patient was asymptomatic with radiographic evidence of minimal persistent disease. In summary, some intraabdominal lymphangiomas have a tendency to induce marked reactive and inflammatory changes in the surrounding tissues, often obscuring their nature and occasionally leading to the clinical impression of a malignant tumor. Awareness of this unusual occurrence will lead to the correct diagnosis.