Neonatal protein-losing enteropathy caused by intestinal lymphatic hypoplasia in siblings

Pathophysiology, Diagnosis, and Management of Canine Intestinal Lymphangiectasia: A Comparative Review

Intestinal lymphangiectasia was first described in the dog over 50 years ago. Despite this, canine IL remains poorly understood and challenging to manage. Intestinal lymphangiectasia is characterized by variable intestinal lymphatic dilation, lymphatic obstruction, and/or lymphangitis, and is a common cause of protein-losing enteropathy in the dog. Breed predispositions are suggestive of a genetic cause, but IL can also occur as a secondary process. Similarly, both primary and secondary IL have been described in humans. Intestinal lymphangiectasia is definitively diagnosed via intestinal histopathology, but other diagnostic results can be suggestive of IL. Advanced imaging techniques are frequently utilized to aid in the diagnosis of IL in humans but have not been thoroughly investigated in the dog. Management strategies differ between humans and dogs. Dietary modification is the mainstay of therapy in humans with additional pharmacological therapies occasionally employed, and immunosuppressives are rarely used due to the lack of a recognized immune pathogenesis. In contrast, corticosteroid and immunosuppressive therapies are more commonly utilized in canine IL. This review aims toward a better understanding of canine IL with an emphasis on recent discoveries, comparative aspects, and necessary future investigations.

Primary intestinal lymphangiectasia in children: A review

Primary intestinal lymphangiectasia is an uncommon condition that usually presents early in childhood. This incurable condition is consequent to underlying lymphatic abnormalities that lead to loss of lymphatic contents into the intestinal lumen. This article outlines an approach to the assessment of children presenting with characteristic features and consideration of other conditions that could lead to enteric protein loss. An overview of the management of primary intestinal lymphangiectasia is outlined.

Small Intestinal Lymphatic Hypoplasia in Three Dogs with Clinical Signs of Protein-losing Enteropathy

Intestinal lymphatic hypoplasia (ILH) is a rare but well-documented cause of protein-losing enteropathy (PLE) in human infants. To our knowledge, this condition has not been reported previously in veterinary medicine. Here we report the clinical and histopathological findings in three dogs that presented with clinical signs of PLE. The onset of PLE was early in an 18-month-old Great Pyrenees, while the other two dogs, a pug and a Tibetan terrier, had a later onset at 4 and 12 years of age, respectively. The presence of intestinal lymphatic and blood vessels was assessed by immunohistochemistry for human prospero homeobox 1 (prox-1), a lymphatic endothelial nuclear transcription factor and human von Willebrand factor (vWf), a marker of vascular endothelial cells, respectively. Small intestinal specimens taken from each dog showed severe mucosal oedema with a lack of prox-1 labelling of villous lacteals, dilated and tortuous vWf immunoreactive villous arterial and capillary blood vessels, and variable lamina propria mixed inflammatory cell infiltrates. Other histological features of ILH included club-shaped villi that were lined by low cuboidal epithelium or epithelial cells with cytoplasmic pallor and microvacuolar change, extrusion zone epithelial inversion and thin and inconspicuous villous longitudinal smooth muscles. While ILH is an uncommon diagnosis, it should be considered as a differential in dogs with clinical signs of PLE. The cause of canine ILH is unknown; however, a congenital abnormality with early or late onset of clinical signs is suspected. Diagnosis of ILH can be challenging; however, immunohistochemical labelling of lymphatic endothelial cells with prox-1 is essential for making this diagnosis.

Gastrointestinal lymphatics in health and disease

Lymphatics perform essential transport and immune regulatory functions to maintain homeostasis in the gastrointestinal (GI) system. Although blood and lymphatic vessels function as parallel and integrated systems, our understanding of lymphatic structure, regulation and functioning lags far behind that of the blood vascular system. This chapter reviews lymphatic flow, differences in lymphangiogenic and hemangiogenic factors, lymphatic fate determinants and structural features, and examines how altered molecular signaling influences lymphatic function in organs of the GI system. Innate errors in lymphatic development frequently disturb GI functioning and physiology. Expansion of lymphatics, a prominent feature of GI inflammation, may also play an important role in tissue restitution following injury. Destruction or dysregulation of lymphatics, following injury, surgery or chronic inflammation also exacerbates GI disease activity. Understanding the physiological roles played by GI lymphatics is essential to elucidating their underlying contributions to forms of congenital and acquired forms of GI pathology, and will provide novel approaches for therapy.

A preterm infant with intestinal lymphangiectasia: a diagnostic dilemma

Intestinal lymphangiectasia (IL) is a potentially fatal disorder of the lymphatic system if it is not recognized and proper treatment initiated. The disease is characterized by lymphocytopenia, peripheral edema, and hypoalbuminemia. Because IL is a rare disease, the symptoms, diagnostic workup, and treatment are unfamiliar to many clinicians. Current literature documents only a few reported cases of IL in a preterm infant. This case report of a preterm infant reviews history, symptomatology, and the diagnostic workup performed. The steps in making the diagnosis, the treatment, and the prognosis of this condition are also presented.

Lymphatics in the alimentary tract of children in health and disease: study on mucosal biopsies using the monoclonal antibody d2-40

Primary intestinal lymphangiectasia and intestinal lymphatic hypoplasia are 2 causes of protein-losing enteropathy in children and share many common clinical features. For the diagnosis of lymphatic hypoplasia on endoscopic biopsies of the intestine, i.e., based on a negative finding in a small specimen, a very sensitive and specific method for identifying lymphatics is essential. In the present study, lymphatic vessels were labelled using D2-40 immunostaining in mucosal biopsy specimens of the alimentary tract of children in whom no histologic abnormality was noted and of those who had different relatively common pediatric conditions, including inflammatory and neoplastic diseases. Using this method, lymphatic vessels were well visualized even in young infants and not destroyed by diseases. The presence of the muscularis mucosae in specimens was important for adequate assessment. In the duodenum and esophagus, lymphatics were observed in every single section; in the stomach, ileum, and colon, they were less regular and several sections were sometimes required. The extreme sensitivity of this method for demonstrating lymphatic vessels in the duodenum makes it ideal for the histologic diagnosis of intestinal lymphatic hypoplasia. In 4 patients who were considered to have this diagnosis based on clinical features, full-thickness intestinal biopsies and electron microscopy, D2-40 immunostaining confirmed the absence or marked paucity of lymphatics.

A case of protein-losing enteropathy caused by intestinal lymphangiectasia in a preterm infant

Intestinal lymphangiectasia is characterized by obstruction of lymph drainage from the small intestine and lacteal dilation that distorts the villus architecture. Lymphatic vessel obstruction and elevated intestinal lymphatic pressure in turn cause lymphatic leakage into the intestinal lumen, thus resulting in malabsorption and protein-losing enteropathy. Intestinal lymphangiectasia can be congenital or secondary to a disease that blocks intestinal lymph drainage. We describe the first case of intestinal lymphangiectasia in a premature infant. The infant presented with peripheral edema and low serum albumin; high fecal concentration of alpha(1)-antitrypsin documented intestinal protein loss. Endoscopy showed white opaque spots on the duodenal mucosa, which indicates dilated lacteal vessels. Histology confirmed dilated lacteals and also showed villus blunting. A formula containing a high concentration of medium chain triglycerides resulted in a rapid clinical improvement and normalization of biochemical variables. These features should alert neonatologists to the possibility of intestinal lymphangiectasia in newborns with hypoalbuminemia and peripheral edema. The intestinal tract should be examined for enteric protein losses if other causes (ie, malnutrition and protein loss from other sites) are excluded. The diagnosis rests on jejunal biopsy demonstrating dilated lymphatic lacteal vessels.