Case of the month: lymphangiomatosis marmoset


Annika Herrmann

Board Certified Anatomic Pathologist

Ben, a 2 year old Marmoset monkey.

Clinical history

Ben had a history of a fluid-filled swelling in the mammary area. Previously, fluid was sampled and was found to be of low cellularity. Lesions progressed with erythematous skin and secondary pyoderma over the entire ventrum and thickened, sore scrotal skin.


The biopsies submitted were representative of subcutaneous adipose and some fibrous connective tissue. Dissecting between the adipose and fibrous connective tissue were variably ectatic irregular and branching channels filled with clear space and rarely some erythrocytes. These channels were lined by flat and histologically unremarkable endothelial cells. No mitotic figures were observed in 2.37 mm2 that were examined (equivalent to 10 high power fields (x400)).

Fig. 1: The biopsy is composed of subcutaneous adipose and fibrous connective tissue. Empty channels dissecting between the tissue are already observed at low magnification (x10); examples of channels marked with arrowheads.

Fig. 2: Higher magnification of channels (x200). The channels are mostly empty, only rare erythrocytes are observed (blue arrowhead). The channels are lined by histologically unremarkable endothelial cells (red arrowhead).


Consistent with lymphangiomatosis, skin, mammary area.

Note: Definitive confirmation of a lymphatic proliferation requires IHC for the lymphatic endothelial marker LYVE-1. However, based on the combination of clinical history and histologic appearance, lymphangiomatosis was considered the most likely diagnosis.

What is Lymphangiomatosis?

Lymphangiomatosis is a rare congenital disorder thought to represent a malformation arising from failure of primitive lymphatic systems to adequately separate from or communicate with the venous system. Though the disorder is not thought to be neoplastic, progression and recurrence frequently occur.

In humans the disorder occurs primarily in children and rarely manifests after the first two decades.

In animals, lymphatic malformations are very rare. The reports available mostly describe cutaneous lymphangiomatosis in dogs and cats with rare reports in other species. The lesions are most frequently observed on the abdomen, ventral neck, inguinal area, prepuce and legs. Other lymphatic malformations are rarely reported in dogs and have been observed in the retroperitoneum, abdominal cavity, spleen and liver. As in humans, mostly young animals are affected, although a case of lymphangiomatosis in an old dog has been published.

Cutaneous lymphangiomatosis clinically presents as poorly demarcated, fluctuant swellings, that are often progressive. Tracts and ulcers may occur and may drain serous fluid.

Histologically, the lesion is characterised by a poorly circumscribed mass composed of angular, dilated and partially interconnected channels, which may contain some proteinaceous fluid; erythrocytes are rarely observed. The channels are lined by inconspicuous endothelium with no cellular atypia and minimal or no mitotic activity.

Lymphangiomatosis must be differentiated from clinically and histologically well-demarcated lymphangiomas, for which progression and recurrence after complete local resection would not be expected.

To the best of the author’s knowledge, lymphangiomatosis has not been described in marmosets, so far.


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