State-of-the-art diagnostic tool applied to lymphology. With this imaging technique, larger lymphatic structures can be displayed without any contrast medium, hence without any time-consuming preparation work normally required to carry out a more conventional lymphography. Through straightforward computer data processing – namely digital subtraction of adipous tissue – with a standard MR acquisition, the morphology of lymphatic tissues -lymph nodes can be seen.
Lymphangio-MR of the lower extremities, applied for the study of left lower limb lymphedema. Clear difference between the two compared extremities (the different thickness of suprafascial soft tissues is evident).
Post-mastectomy lymphedema of the right upper limb assessed by lymphangio- MR. The arrow points to a dilated lymphatic collector in the arm.
LYMPHANGIODYSPLASIAS (LYMPHATIC DYSPLASIA, LYMPH NODE DYSPLASIA)
They include a wide range of congenital (and acquired) anomalies in the development of the lymphatic system, which may feature lymphatic aplasia, hypoplasia, or hyperplasia. Dysplastic anomalies may affect lymphatic vessels and lymph nodes, either individually or in association, thus leading to complex pathological pictures that have recently been grouped into a nosological classification proposed by C. Papendiek, which comprises three different groups of dysplasias:
- LAD I lymphangiodysplasias;
- LAD II lymphadenodysplasias;
- LAAD lymphangioadenodysplasias.
The most important clinical manifestations of anomalies caused by dysplasia are: cystic hygroma, hydrops foetalis, lymphangioma and, more commonly, syndromes due to chylous and/or lymphatic reflux and peripheral lymphedema
Severe, congenital peripheral lymphedema of the left lower limb, due to lymphangiodysplasia, and, in this specific case, characterized by severe, lymphostatic verrucosis of the toes.
Example of intestinal lymphangiodysplasia, as detected by direct lymphangiogram of both lower extremities.
A radiological method with which, following the injection of lymphotropic and radio-opaque contrast medium (Lipiodol ultrafluid, see), into lymphatic circulation, the general structures of lymphatics, their morphology, and anomalies, if any, can be displayed. This technique developed by Kinmonth in 1955 is carried out in three steps: identification of lymphatic structures by means of a vital stain (Blue Patent Violet, see BPV); surgical isolation of detected collectors; incannulation of collectors with injection of liposoluble contrast medium directly into the collectors or with support from a spiral CT.
Figure: Lymphography of a lower limb identifying markedly ectasic lymphatic collectors (gravitation reflux).
Classified as a differentiated lymphangioblastic tumor, lymphangioma is actually a benign angioblastic tumor, consisting of vasal spaces lined by endothelium, just like in more common angiomas, but differing in that they contain lymph or chyle (chylous angioma). Lymphangiomas are classified by the size of these vasal spaces into: simple lymphangioma, cavernous lymphangioma (with larger spaces), and cystic lymphangioma or hygroma (congenital hamartoma, similar to cavernous lymphangioma, with typical localizations, near embryonic lymph sacs).
Segment of lymphatic collector in between two valves: it is considered to be the functional unit of the peripheral lymphatic system.
Lymphangiosarcoma is a rare malignant soft tissue tumor originating from lymphatic endothelium cells. It grows almost exclusively in tissues affected by chronic incurable lymphedema of various stages and different etiology. The classification and staging of this tumor is still much debated, especially because, from a pathological anatomy point of view, it has many similarities with other tumors of endothelial origin, such as, for example, with hemangiosarcoma. Therefore, considering these elements, in more recent publications, lymphangiosarcoma has been classified as angiosarcoma associated with lymphedema. Because of its aggressive and malignant nature, the average survival is around 18 months after diagnosis. No therapy attempted so far has led to satisfactory results; for now, the only valid therapeutical solution is still surgical “disarticulation” of the affected limb, while hoping that, through early diagnosis, the tumor has not yet metastisized. Some encouraging, although still preliminary results, have recently been reported with hyperthermic perfusion of the isolated extremity with “melphalan”. A significant reduction has been reported in the incidence of lymphangiosarcoma in patients undergoing rigorous medical-physical therapies and microsurgery to treat lymphedema. Indeed, inveterated and neglected lymph stasis, with recurrent and frequent lymphangitic episodes, is allegedly the main agent responsible for cancerous degeneration of the lymphatic endothelium.
Therefore, in conclusion, prevention based on accurate inspection of all lesions developed on a lymphedematous limb, and aimed at early diagnosis, as well as combined, prolonged treatment of lymphedema, are still the only weapons to fight this rare yet intimidating cancer.
Inflammation of the lymphatic vessels. It may be acute or chronic, it may affect superficial (superficial lymphangitis) or deep (deep lymphangitis) lymphatics, or have a reticular involvement, when the network of dermal lymphatics is affected (in which case it is also called acute erysipeloid lymphangitis, owing to its similarities to erysipelas); or with truncular involvement, when mostly the major lymphatic trunks are affected. From an etiopathogenetic point of view, several causes may trigger lymphangitis: infections are for sure the most frequent one, especially those due to streptococci (beta-hemolytic group A Streptococcus), staphylococci (Staphylococcus aureus), coli, and pneumococci. However, lymphangitis pictures can sometimes be observed after traumas, or in association with systemic inflammatory lesions (e.g. in rheumatic diseases). The immune system of the extremity affected by lymph stasis is somehow “deficient”, not so much because of cell impairment – as is the case in systemic immunodeficiency -, but rather because some of the cells in charge of providing adequate immune response (e.g. macrophages, Langerhans cells, or, more generally APC, that is Antigen Presenting Cells) are unable to move about properly. For this reason, a small lesion (such as an insect bite) is sufficient to let saprophyte germs in, thus triggering a lymphangitis episode. From a clinical point of view, lymphangitis may present some severe clinical problems. Indeed, depending on the type of germs that have penetrated into the body, on their bacterial load, and on any local immunodeficiency of the affected individual, even severely acute episodes may take place, in some cases leading to overt septicaemia and life-threatening conditions, which require hospitalization of the patient to an intensive-care unit for proper monitoring of the patient’s vital parameters. More commonly, acute lymphangitis presents with a picture of erythema involving the affected extremity, featuring all the five semeiotic parameters linked to inflammation (rubor, calor, dolor, tumor and laesa functio), associated with hyperpyrexia, (up to 41°C axillary temperature with or without shivering). Antibiotic therapy associated with symptomatic therapy (pain killers, antipyretic drugs), administered during hospitalization of the patient, is so far the treatment of choice. In lymphedema patients or in patients with disorders associated with lymph stasis, antibiotic prophylaxis should be recommended, with slow-release penicillins (one i.m. injection every 2-3 weeks), in order to protect patients from this dangerous complication.
Any total absence of embryo-fetal development of lymphatic structures is practically incompatible with extrauterine life.The majority of congenital clinical manifestations, due to a development deficit of lymphatic structures, are most commonly correlated with anatomic-pathologic pictures of lymphatic structures-lymph node hypoplasia, or, in very rare cases, partial aplasia of major lymphatic structures, such as, for example, the thoracic duct.
Although very complicated and complex, the anatomy of the lymphatic system can be summarized in the following way:
Superficial (suprafascial) circulation: it drains the cutis and the sub-cutis, running parallel to the veins and forming a thick superficial anastomotic network;
Deep (subfascial) circulation: it drains the muscles, joints, and tendons; its main branches run along the vascular-nervous bundles; – Visceral Circulation: it drains internal abdominal and thoracic organs. Perforating lymphatic vessels connect the superficial lymphatic circulation with the deep one. For a more detailed description, please refer to specific books on human systematic and topographic anatomy.
They are pathways for proper lymphatic drainage. They are organized into a complex and widespread anastomotic network punctuated by lymph node structures. For this reason, they are classified into afferent (or prelymph node) and efferent (or postlymph node) collectors. Further, depending on their anatomic position, they are classified into superficial (or suprafascial) and deep (or subfascial), and visceral collectors.