Kaposiform Hemangioendothelioma
Kaposiform hemangioendothelioma (KHE) is a rare vascular neoplasm that is locally aggressive but without metastatic potential. It occurs particularly in the skin, deep soft tissue, retroperitoneum, mediastinum, and rarely in bone. Although lesions occur solitary, they often involve large areas of the body, such as the head/neck region (40%), trunk (30%), or extremity (30%). Usually, it is present at birth as a flat, reddish-purple, tense and edematous lesion. Although half of lesions are congenital, 58% of KHE develop during infancy, 32% between age 1 and 10 years (32%) and 10% after 11 years of age. Moreover, adult onset has been described too with mainly males being affected. Both sexes are affected equally in children. Lesions are often greater than 5 cm in diameter and can cause visible deformity and pain. During early childhood, KHE may enlarge and after 2 years of age, it may partially regress. Though, it usually persists longterm. In addition, 50% of patients suffer from coagulopathy due to thrombocytopenia (<25,000/mm3), presenting with petechiae and bleeding.
This is called the Kasabach-Merritt Phenomenon, which is caused by trapping of platelets and other clotting factors within the tumor. Kasabach-Merritt Phenomenon is less likely in patients with lesions less than 8 cm. As two-thirds of adult-onset KHE tumors are less than 2 cm, KHE in adults is rarely associated with Kasabach-Merritt Phenomenon. Patients with KHE and Kasabach-Merritt Phenomenon present with petechiae and ecchymosis. Most KHE tumors are diffuse involving multiple tissue planes and important structures. Resection of KHE is thus often difficult. Treatment of kaposiform hemangioendothelioma is therefore medical. The primary drug is interferon alfa, which is successful in 50% of children. Another option is vincristine, which has lots of side-effects, but has a response rate of 90%. Drug therapy is often used in shrinking the tumor and treating the coagulopathy. However, many of these kaposiform hemangioendotheliomas do not completely regress and remain as a much smaller asymptomatic tumor. However, KHE still has a high mortality rate of 30%. Although complete surgical removal with a large margin has the best reported outcome, it is usually not done because of the risk of bleeding, extensiveness, and the anatomic site of the lesion. Operative management may be possible for small or localized lesions. Removal of larger areas also may be indicated for symptomatic patients or for patients who have failed pharmacotherapy. Resection is not required for lesions that are not causing functional problems, because KHE is benign and because resection could cause deformity.
Pyogenic Granuloma
Pyogenic granuloma, also known as lobular capillary hemangioma, is a small benign vascular tumor that primarily involves the skin (88.2%) and mucous membranes. Pyogenic granuloma appears as a red macule that grows rapidly, turns into a papule and eventually becomes pedunculated, being attached to a narrow stalk. The average diameter of these lesions is 6.5 mm. Although these lesions are small, they are often complicated by bleeding, crusting and ulceration. Microscopically, pyogenic granulomas are characterized by vascular proliferation amidst granulation tissue and chronic inflammatory infiltrate.
Pyogenic granulomas are rarely congenital. It commonly develops in infants: 42.1% develops within the first 5 years of life. This vascular tumor is twice as common in males as in females and 25% of lesions seem to be associated with trauma, an underlying cutaneous condition, pregnancy, hormonal alterations and medications. Pyogenic granulomas can also arise within a capillary malformation. Of all pyogenic granulomas, 62% is distributed on the head or neck, occurring mainly on the cheek and in the oral cavity. Lesions on the face may cause visible deformity.
Numerous treatment methods have been described for pyogenic granuloma. Lesions involving the reticular dermis, may be out of the reach of pulsed-dye laser, cautery or shave excision and therefore have a recurrence rate of 43.5%. Definitive management requires full-thickness skin excision. Other options are curettage or laser therapy. Furthermore, thorough curettage and cauterization are often used for small lesions and full-thickness excision for larger lesion.
Vascular Malformations
Vascular malformation is a collective term for different disorders of the vasculature (errors in vascular development). It can be a disorder of the capillaries, arteries, veins and lymphs or a disorder of a combination of these (lesions were named based on the primary vessel that was malformed). A vascular malformation consists of a clew of deformed vessels, due to an error in the vascular development (dysmorphogenesis). However, endothelial turnover is stable in these defects. Congenital vascular malformations are always present at birth, although they are not always visible. In contrast to vascular tumors, vascular malformations do not have a growth phase, nor an involution phase. Vascular malformations tend to grow proportionately with the child. Vascular malformations never regress, but persist throughout life. Vacular malformations can be divided in slow-flow vascular malformations, fast-flow vascular malformations and complex-combined vascular malformations.
Slow-Flow Vascular Malformations
- Capillary malformation (also known as port-wine stain): Capillary malformations are flat, reddish lesions that typically affect the skin, mostly around the head and the neck, who darken with age, contrary to birthmarks such as salmon patch, Nevus simplex or vascular stain, who lighten or disappear within the first few years of life. Capillary malformations are 11% of the vascular malformations. Syndromes associated with capillary malformations are: Sturge-Weber syndrome and Klippel-Trenaunay syndrome. Capillary malformations can be treated with IPL-(Intensed-pulsed-light)-therapy or surgical reduction.
- Venous malformation is a bluish lesion compressible on palpation, the masses enlarge with physical activity or a dependent position. The bluish lesion is caused by dilated venous channels. Venous malformations can be painful in the morning due to stasis and microthrombi within the veins. Venous malformations’ localization is usually in the head and neck. Venous malformations are the most common vascular anomaly, they are 40% of all vascular malformations. Venous malformation can be treated with sclerotherapy and surgical reduction.
- Lymphatic malformation is a benign growth of the lymphatic system. They result from a blockage or defect of the lymphatic vessels as they are forming. 28% of all vascular malformations consists of lymphatic malformations. Lymphatic malformations can be treated with sclerotherapy and surgical reduction.
Fast Flow Vascular Malformations
- All fast flow malformations are malformations with an arterial type in it. Contain about 14% of the vascular malformations.
Arterial malformation
- Arteriovenous fistula (AVF) : a lesion with a direct transition in fistulas between an artery and a vein.
- Arteriovenous malformation : a lesion with a direct connection between an artery and a vein, without an intervening capillary bed, but with an interposed nidus of dysplastic vascular channels in between.
Congenital Nevus
Congenital melanocytic nevus is a type of melanocytic nevus (or mole) found in infants at birth. This type of birthmark occurs in an estimated 1% of infants worldwide; it is located in the area of the head and neck 15% of the time.
Congenital melanocytic nevi may be divided into the following types:
- Small-sized congenital nevocytic nevus is defined as having a diameter less than 2 cm.
- Medium-sized congenital nevocytic nevus is defined as having a diameter more than 2 cm but less than 20 cm.
- Giant congenital melanocytic nevus (also known as “Bathing trunk nevus,” “Garment nevus,” “Giant hairy nevus”, and “Nevus pigmentosus et pilosus”) is defined by one or more large, darkly pigmented and sometimes hairy patches.
Signs and Symptoms
The congenital melanocytic nevus appears as a circumscribed, light brown to black patch or plaque, potentially very heterogeneous in consistency, covering any size surface area and any part of the body.
As compared with a melanocytic nevus, congenital melanocytic nevi are usually larger in diameter and may have excess terminal hair, a condition called hypertrichosis. If over 40 cm projected adult diameter with hypertrichosis, it is sometimes called giant hairy nevus; more usually these largest forms are known as large or giant congenital melanocytic nevus. The estimated prevalence for the largest forms is 0.002% of births.
Melanocytic Nevi often grow proportionally to the body size as the child matures. As they mature, they often develop thickness, and become elevated, although these features can also be present from birth. Prominent terminal hairs often form, especially after puberty. With maturity, the nevus can have variation in color, and the surface might be textured with proliferative growths.
Diagnosis
Benign congenital nevi can have histological characteristics resembling melanomas, often breaking most if not all of the ABCD rules. Dermatoscopic findings of the smaller forms of benign congenital nevi can aid in their differentiation from other pigmented neoplasms.
Microscopically, congenital melanocytic nevi appear similar to acquired nevi with two notable exceptions. For the congenital nevus, the neval cells are found deeper into the dermis. Also, the deeper nevus cells can be found along with neurovascular bundles, with both surrounding hair follicles, sebaceous glands, and subcutaneous fat. Such annexes and the hypodermis can also be hypoplasic or, conversely, present aspects of hamartoma.
Treatment
Surgical excision is the standard of care. Some individuals advocate the use of hair removal laser for the treatment of congenital nevi. While this is likely safe and effective for small congenital nevus, laser removal for larger lesions might pose a liability for the laser surgeon if malignancy developed from a deep (dermal) component of the nevus that is not reached by the laser. Repigmentation after laser treatment of congenital nevi or superficial curettage supports this concern.
Many are surgically removed for aesthetics and relief of psychosocial burden, but larger ones are also excised for prevention of cancer, although the benefit is impossible to assess for any individual patient. Proliferative nodules are usually biopsied and are regularly but not systematically found to be benign. Estimates of transformation into melanoma vary from 2-42% in the literature, but are most commonly considered to be at the low end of that spectrum due to early observer bias.
Prognosis
Large and especially giant congenital nevi are at higher risk for malignancy degeneration into melanoma. Because of the premalignant potential, it is an acceptable clinical practice to remove congenital nevi electively in all patients and relieve the nevocytic overload.
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