Lymphedema. Etiopathogenesis

A Case Report of Presumptive Primary Lymphedema Localized to the Face of a Dog

Primary lymphedema (PLE) is an uncommon diagnosis in veterinary medicine, with most of the previously described cases showing lower limb edema associated with a guarded long-term prognosis. To the authors' knowledge, this case report describes the first case of lymphedema localized unilaterally to the facial region of one-year-old German Shorthair Pointer, in which indirect CT-lymphography, combined with histopathologic examination of the skin, resulted in a tentative diagnosis of PLE.

Dietary supplements in lymphedema

Lymphedema is a chronic inflammatory disorder resulting from ineffective fluid uptake by the lymphatic system, and the effects are principally felt in the lower limbs. The condition is said to be primary when caused by genetic mutations and secondary when caused by injuries, infections, or surgery. Lymphedema, a worldwide pathology, does not have an effective therapy so far. Leukotriene B4 has recently been identified as a key molecule in lymphedema pathogenesis. Surgical, nonsurgical, and pharmacological treatments have been proposed; however, they do not cure the disease and only ameliorate the symptoms. Nutrition and nutritional status are extremely important in lymphedema physiopathology. Obesity is a comorbidity that exacerbates the risk for secondary lymphedema and constitutes a negative prognostic factor. Indeed, anti-inflammatory foods and their effects on the inflammatory state and on oxidative stress are now being investigated for their possible therapeutic role in lymphedema. Although no special diet has so far been proven to be very effective, specific dietary tips could help in alleviating the edematous state of patients with lymphedema. A few supplements have been tested for lymphedema treatment. Among them, GARLIVE^® containing hydroxytyrosol, hesperidin, spermidine and vitamin A, exhibited promising effects in the animal model. Hydroxytyrosol, a polyphenol from olives, showed anti-inflammatory effects and reduced leukotriene B4 synthesis, thus holding promise as a potential natural candidate for lymphedema treatment.

Low Efficacy of Genetic Tests for the Diagnosis of Primary Lymphedema Prompts Novel Insights into the Underlying Molecular Pathways

Lymphedema is a chronic inflammatory disorder caused by ineffective fluid uptake by the lymphatic system, with effects mainly on the lower limbs. Lymphedema is either primary, when caused by genetic mutations, or secondary, when it follows injury, infection, or surgery. In this study, we aim to assess to what extent the current genetic tests detect genetic variants of lymphedema, and to identify the major molecular pathways that underlie this rather unknown disease. We recruited 147 individuals with a clinical diagnosis of primary lymphedema and used established genetic tests on their blood or saliva specimens. Only 11 of these were positive, while other probands were either negative (63) or inconclusive (73). The low efficacy of such tests calls for greater insight into the underlying mechanisms to increase accuracy. For this purpose, we built a molecular pathways diagram based on a literature analysis (OMIM, Kegg, PubMed, Scopus) of candidate and diagnostic genes. The PI3K/AKT and the RAS/MAPK pathways emerged as primary candidates responsible for lymphedema diagnosis, while the Rho/ROCK pathway appeared less critical. The results of this study suggest the most important pathways involved in the pathogenesis of lymphedema, and outline the most promising diagnostic and candidate genes to diagnose this disease.

Lymphangiomatosis of the systemic skin in an old dog

A 13-year-old, neutered male miniature dachshund was presented with a one-month history of bilateral symmetrical swelling in the pinnae and carpal, cubital and tarsal joints, and swelling in the tail. The lesions were histopathologically characterized by multiple dilated lymphatic vessels lined by a single attenuated layer of endothelial cells. The subcutis was predominantly involved. A number of spindle-shaped cells lining the irregular vessels were observed. Morphological atypia was not evident in these cells. Immunohistochemical analyses revealed that the proliferating endothelial cells were positive for factor VIII-related antigen and CD31. Based on the clinical presentation and histopathological features, the dog was diagnosed with lymphangiomatosis. Treatment with anti-inflammatory prednisolone improved the symptoms.

Secondary malignant lymphoedema after mastectomy in two dogs

This case report describes the diagnosis of secondary malignant lymphoedema in two dogs that had undergone a mastectomy. A remarkable severe oedematous lesion associated with lameness in the right hindlimb was observed in both cases. Diagnostic imaging examinations, including direct pedal lymphangiography (case 1) and lymphoscintigraphy (case 2), showed obstruction of lymph flow in the lymphatics of the right hindlimbs. Although the recommended medical management and physiotherapy had been applied to resolve the problems, oedema did not improve in the damaged region in both cases. Results of histopathological examinations suggested that the cause of the obstructed lymph flow was neoplastic cells in the lymphatics of the right hindlimb in both dogs.

Lymphatic drainage on healthy and neoplasic mammary glands in female dogs: can it really be altered?

The purpose of this research was to study the mammary lymphatic drainage under a macroscopic and mesoscopic view, comparing the vascular pattern of healthy and neoplasic mammary glands injected with drawing ink alcoholic and fluorescein solutions, in 46 mongrel female dogs. The results pointed out that the thoracic gland is drained by the axillary lymph centre, but in mammary neoplasia either superficial cervical or ventral thoracic lymph centres can be involved. Cranial and caudal abdominal glands may be drained by the axillary, inguinofemoral and popliteal lymph centres. However, the popliteal drainage is specific for the healthy caudal abdominal mammary gland. The inguinal gland can be drained by both inguinofemoral and popliteal lymph centres in both neoplasic and healthy conditions. Regarding the mammary lymphatic communications, this research demonstrated that neoplasic glands present more types of anastomosis (40.9%), than healthy glands (33.33%), and an increase in contralateral anastomosis (50%) compared with healthy ones (33%). Given the data, the mammary neoplasia can change the lymphatic drainage pattern in terms of lymph centres and vascular arborization, thus forming new drainage channels and recruiting a larger number of lymph nodes. Lastly, some comments were made about the severity of a specific neoplasic mammary gland and conditions to be considered before making a decision in terms of the most adequate operative procedure, and suggestions for further investigations.

Chylous effusions revisited

Varying terms and criteria have been used in the veterinary literature to characterize milky opaque pleural effusions through the years. This article addresses ideas widely repeated in the veterinary and human literature upon which time, experience, diagnostic techniques, experimental data, and improved understanding of pathogenesis have cast doubt. Topics discussed include terminology, pathogenesis of chylous and pseudochylous effusions, criteria for differentiation of chylous from pseudochylous effusions, and clinicopathologic changes associated with drainage of chylous effusions.

Evaluation of the pathology, pathogenesis and aetiology of auricular elephantiasis in slaughter pigs

Ears from slaughter pigs with auricular elephantiasis (n = 24) and the corresponding lymph nodes (lnn.) (n = 26) were grossly, histopathologically and microbiologically examined. Immunostaining for IgM, IgG, Cd3epsilon and bacterial antigens of Arcanobacterium pyogenes and Staphylococcus aureus was performed by indirect enzyme-based techniques. Ears were variably thickened depending on the sampled area (basis, centre and apex). However, at all locations the thickness, the length from basis to apex and the weigh of whole ears with elephantiasis were significantly increased (P < 0.01). The corresponding lnn., that is, ln. parotideus superficialis and profundus, had also increased significantly (P < 0.01) in volume. Histopathologically, lesions of the ears and the corresponding lnn. revealed changes characterized by diffuse fibrosis intermingled with multiple pyogranulomatous foci containing asteroid bodies. In the majority of lesions, four distinct zones due to different cellular infiltrates encircled the central core of the asteroid bodies. In several lesions, the pyogranulomatous foci were contained within the lymph vessels. Immunohistochemically, only the bacterial antigen of S. aureus was detected within the cytoplasm of the macrophages and/or in the asteroid bodies of the ears (41.5%) and in the regional lnn. (30.8%). An abundant number of IgM, IgG and CD3epsilon-positive cells were present in all the pyogranulomatous lesions, whereas a positive IgG-staining was observed only in a single asteroid body. Thus, porcine auricular elephantiasis is a chronic pyogranulomatous inflammation that is frequently positive for S. aureus and is lymphogenically spread. Therefore, the lesions of the ears with auricular elephantiasis and the corresponding lnn. should be termed auricular botryomycosis and botryomycotic lymphadenitis, respectively. Moreover, as the disease is observed frequently in slaughter pigs it must also be considered according to the welfare of the animals and in relation to post-mortem meat inspection.

Hyperplasia of lymphatic vessels in VEGF-C transgenic mice

No growth factors specific for the lymphatic vascular system have yet been described. Vascular endothelial growth factor (VEGF) regulates vascular permeability and angiogenesis, but does not promote lymphangiogenesis. Overexpression of VEGF-C, a ligand of the VEGF receptors VEGFR-3 and VEGFR-2, in the skin of transgenic mice resulted in lymphatic, but not vascular, endothelial proliferation and vessel enlargement. Thus, VEGF-C induces selective hyperplasia of the lymphatic vasculature, which is involved in the draining of interstitial fluid and in immune function, inflammation, and tumor metastasis. VEGF-C may play a role in disorders involving the lymphatic system and may be of potential use in therapeutic lymphangiogenesis.