Case series on vascular malformation and their review with regard to terminology and categorization.

Malformations of vascular nature originate as anomalies caused due to errors in vasculogenesis. These tumors are generally broadly classified into vascular tumors (hemangiomas) and vascular malformations (venous malformations, arteriovenous malformations, lymphatic malformations). These descriptive tumors and malformations have been categorized based on the architectural assembly of vessels. Lymphangiomas are further subclassified microscopically into capillary, cavernous, cystic and lymphangioendothelioma, depending upon their histopathological features. Lymphatic malformations or lymphangiomas are uncommon congenital malformations of the lymphatic system, usually occurring in the head and neck region, characterized by collections of ectatic lymph vessels that form endothelial lined cystic spaces. Advancements in the knowledge of pathogenesis of such vascular malformations are continuously changing their treatment protocols. Early recognition is of utmost importance for initiation of proper treatment and avoiding serious complications. Hemangiolymphangioma is a variant of lymphangioma showing vascular component. Herewith, we present a case of vascular malformation diagnosed as hemangiolymphangioma histopathologically in a 9-year-old girl, along with a review of literature regarding its categorization.

Introduction

The need for categorization of anomalies and congenital aberrancies formed due to developmental vascular defects produce identifiable birthmarks of the skin and mucosa and a variable degree of underlying soft tissue abnormalities.[1] Presently a surge in the knowledge of criterias to classify these various anomalies has put forth classifications purely with respect to histopathological features of the disease. These lesions predominantly occur within the head and neck and affect approximately 1 in 22 children.[2] Involvement of the oral cavity is common but frequently requires unconventional treatment strategies for its management.

Though previously termed “angiomas” or vascular “birthmarks”, vascular anomalies are divided into two main categories: vascular tumors and vascular malformations. Infantile hemangiomas comprise the majority of vascular anomalies and are considered the predominant vascular tumor type composed of rapidly proliferating endothelial cells.[2] Blood vessel architecture is incomplete and surrounded by hyperplastic cells in hemangiomas and other vascular tumors. In contrast, vascular malformations do not contain hyperplastic cells but consist of progressively enlarging aberrant and ectatic vessels composed of a particular vascular architecture such as veins, lymphatic vessels, venules, capillaries, arteries or mixed vessel type. The latter comprises lymphangiomas or lymphatic malformations which are congenital collections of ectatic lymph vessels that form endothelial lined cystic spaces.[3] The pathogenesis of these tumors could be of importance in thoroughly understanding the mode of these varying histopathological presentations.

Lymphangiomas are benign, relatively rare tumors characterized by proliferation of lymphatic vessels. They represent about 6% of the total number of benign tumors of the soft tissue in patients aged less than 20 years.[4] Regarding gender distribution of lymphangioma, it is equally divided between males and females, with about 50% of the lesions being noted at birth and 90% developing by 2 years of age.[5]

Oral lesions may occur at various sites but they form most frequently on the anterior two thirds of tongue. They may increase in size, producing macroglossia which may lead to difficulties in mastication, deglutition, and speech; and displacement of the teeth, with a resulting malocclusion. They may interfere with normal breathing, particularly during sleep, produce sleep apnea, and in certain instances, produce a life-threatening upper airway compromise.[6] They can also be present in the palate, buccal mucosa, gingiva and lip.[5]

The tumor is superficial in location and demonstrates a white pebbly surface that resembles a cluster of translucent vesicles. The deeper lesions could mimic various soft tissue tumors since the color which is classically used for diagnosing such tumors would seem to be irrelevant. They appear as a nodule or masses without significant change in surface texture or color.

Case Report

A 9-year-old female patient reported to the Department of Oral & Maxillofacial Pathology, I.T.S CDSR, with a complaint of a painless growth with respect to left side of tongue. Patient had given a history of trauma due to tongue bite around 3 months back and was enlarging slowly in size The swelling was initially small, peanut sized, which increased to the present size. On examination of the swelling a growth of 2 × 1 cm on the anterior part of the dorsal surface of tongue. It appeared to have a pebbly surface that resembled clusters of translucent vesicles. The lesion was pale pink in color and oval in shape with well-defined margins [Figure 1].

Figure 1

Intraoral photograph showing nodular swelling resembling cluster of vesicles on the left side of dorsum of tongue

An incisional biopsy was performed and the tissue was histopathologically diagnosed as lymphangioma, since large lymphatic vessels lined by flattened endothelial cells pushing into the overlying epithelium were seen [Figure 2]. Patient was recalled after 4 days and a total excision of the lesion was performed under local anesthesia (LA). The excised tissue was submitted to the Department of Oral Pathology for histopathological examination.

Figure 2

Photomicrograph of incisional biopsy showing large lymphatic vessels (H and E, ×10)

Examination of gross macroscopic appearance revealed the excised tissue to be oval shaped, measuring 1.5 × 1 cm in size and was creamish brown in color with a pebbly surface.

Microscopic examination of the excised lesion showed numerous large, dilated lymphatic channels of irregular shape, lined by flattened endothelial cells, of which some of the vessels were filled with lymph. The channels were seen abutting and elevating the overlying epithelium [Figure 3]. Numerous large- to medium-sized channels with thin endothelial lining, engorged with RBCs, were also present in the deeper area of the connective tissue [Figure 3, Inset]. A confirmatory diagnosis of hemangiolymphangioma was given.

Figure 3

Photomicrograph showing numerous dilated lymphatic channels abutting the epithelium (H&E, ×10). Inset showing lymphatic channels lined by thin endothelial cells containing lymph. (H and E, ×40)

Discussion

Lymphangioma was first described by Virchow in 1854, and in 1872, Krester hypothesized that hygromas were derived from lymphatic tissue. The origin of lesion is considered to be congenital abnormality of lymphatic system rather than true neoplasm. A portion of the jugular lymphatic sac is thought to sequestrate from the primary sacs during fetal development with failure to establish communications with other lymphatic system.[7] The fact that most lymphangiomas manifest clinically during early childhood and develop in areas where the primitive lymph sacs occur (neck, axilla) provides presumptive evidence for this hypothesis. On the contrary, it is argued that instead of being a congenital malformation, lymphangioma is a true neoplasm resulting from transformed lymphatic endothelial cells and/or stromal cells.[8]

The pathophysiology of vascular malformation, hemangioma and lymphangioma are interrelated. The classic sequence of events in embryology and development of vasculogenesis falls into three stages: the undifferentiated capillary network stage, the retiform developmental stage and the final developmental stage.[9] Two major theories have been proposed to explain the origin of lymphangiomas.[10] The first theory is that the lymphatic system develops from five primitive sacs arising from venous system. Concerning the head and neck, endothelial outpouchings from the jugular sacs spread centrifugally to form the lymphatic systems. Another theory proposes that the lymphatic system develops from mesenchymal clefts in the venous plexus reticulum and spreads centripetally toward the jugular sacs. Finally, lymphangioma develops from congenital obstruction or sequestration of the primitive lymphatic enlargement.[11]

Several studies have been published regarding possible lymphangiogenic growth factor involvement in the etiology of lymphatic malformations. These factors include vascular endothelial growth factor (VEGF)-C, vascular endothelial growth factor receptor 3 (VEGFR-3), and transcription factor Prox-1. VEGF-C and VEGFR-3 have been shown to be upregulated in lymphatic malformed tissue, and both are involved in lymphatic tissue proliferation.[12] Oral lesions are most frequently found on tongue. The tumor may be localized in a small area of tongue or floor of mouth or it may diffusely infiltrate these areas. If the tumor is located in a deeper area, it may present as submucosal mass.[13] Cervical lesions in a child cause dysphagia and airway obstruction which is rare in adults.

The misunderstanding on the nosologic distinction between oral hemangiomas and vascular malformations leads to diagnostic mistakes. Hemangiomas are differentiated from vascular malformations by their clinical appearance, histopathological features, and biologic features. The natural history of hemangiomas involves rapid proliferations for the first several months of life with subsequent spontaneous regression. Vascular malformations are often recognized at birth and grow proportionately with the child, with many becoming more prominent at puberty. Histologically, hemangiomas in the proliferating phase show endothelial hyperplasia and large number of mast cells. In contrast, vascular malformations show normal number of mast cells, and consist of mature, often combined, capillary, arterial, venous, and lymphatic elements.[1]

Lymphatic malformations/lymphangiomas are classified microscopically into four categories:[14] lymphangioma simplex (lymphangioma circumscriptum) composed of small, thin-walled lymphatics; cavernous lymphangioma comprising dilated lymphatic vessels with surrounding adventitia; cystic lymphangioma (cystic hygroma) consisting of huge, macroscopic lymphatic spaces with surrounding fibrovascular tissues and smooth muscle; and benign lymphangioendothelioma (acquired progressive lymphangioma), in which lymphatic channel dissects through dense collagen bundles.

Occasionally, channels may be filled with blood, a mixed hemangiolymphangioma, an uncommon developmental anomaly with a propensity to invade underlying tissues and to recur locally, distinguishing it from the simple lymphangioma or hemangioma.[15] Although histologically it is a benign disorder, local invasion into the muscle, bone, and underlying tissue can lead to severe deformity. In the present case, numerous large-sized lymphatic channels along with medium- to large-sized channels entrapped with RBCs, lined by endothelium, were seen and hence it was subcategorized as hemangiolymphangioma.

We reviewed the archival cases of lymphatic malformations in our department, the demographical information, location and histopathological features of which are shown in Table 1. The only significant difference in the three archival cases and the present case was in the histopathological features of lymphangioma and hemangiolymphangioma.

Table 1

The demographic information, location and histopathological features

These anomalies present the necessity for sound discretion with regards to their approach therapeutically.Although spontaneous regression of lesions is rarely encountered, the treatment seems to weigh heavily on individual assessments of the observer. Aspiration of the cystic content is a temporary measure to relieve airway obstruction. Sclerosing agents are ineffective, probably as a result of the discontinuous basement membrane of the lymphatic vessels. Nd-YAG laser surgery has been widely preferred because of its advantages of less bleeding and edema. Surgical excision is the usual treatment of lymphangioma.[16] Due to a rate of recurrence of nearly 21%, long-term follow-up is essential of these tumorigenic anomalies.

Conclusions

Vascular anomalies like hemangioma and lymphangioma are interlinked in their pathogenesis. The vascular lesions consist of both blood vessels and lymphatic vessels. Whether these can be termed as hemangiolymphangioma or just vascular malformation is still confusing. Thus through the present article we would like to highlight the complexities which can arise from the terminal categorization of the large group of tumors called vascular neoplasms when based on their histopathological representation. Further detailed analysis of a larger case series would be imperative in the correct classification and diagnosis which could enormously help to accurately ascertain prognosis and direct treatment.