Pyogenic granuloma, often referred to by many other names, including lobular capillary hemangioma, is a benign vascular hyperplasia that tends to occur on the gingiva, lips, nasal mucosa, face, and hands.1,2 The lesion often is preceded by minor trauma, has a history of bleeding easily, and appears as a pedunculated or sessile papule with a rough red surface. There is a well-known tendency toward local recurrence after treatment.3 Results of a histopathologic examination shows lobular aggregates of capillaries and venules with plump endothelial cells.4 The pathogenesis of this lesion is poorly understood.
Port-wine stains are a type of nevus flammeus that present as a deep red or purple macule and are typically unilateral.4 Unlike salmon patches, the other type of nevus flammeus, port-wine stains tend to persist into adulthood.5 These congenital malformations are composed of capillary and venule ectasia in the dermis, and the ectasias progress over the course of a lifetime with increasing erythrocyte stasis.6-8 As Finley6 pointed out, in time, the port-wine stain can develop a thickened "cobblestone pattern," as well as nodules that are thought to be arteriovenous malformations or "localized tumor formations." Klapman and Yao8 recently noted that the thickening and nodules are most likely to occur in the areas of the face innervated by the second and third branches of the trigeminal nerve than in other parts of the body. Port-wine stains have been associated with other abnormalities such as nevus anemicus, glaucoma, choroidal angiomas, and Sturge-Weber syndrome.4 The pathogenesis of the port-wine stain has been a controversial issue, but one possibility is that it represents a deficiency of sympathetic innervation of blood vessels.4
The occurrence of vascular neoplasms arising in capillary malformations is a rare, but documented, event.9 Pyogenic granulomas infrequently have been reported to occur in association with other vascular abnormalities such as port-wine stains or hemangiomas, particularly after laser treatment.10,11 A number of other vascular neoplasms, such as capillary hemangiomas, tufted angiomas, and cavernous hemangiomas, have been reported in association with port-wine stains, as well.6,12,13 Very few pyogenic granulomas have arisen in port-wine stains without a history of trauma, laser treatment, or pregnancy. We now report a pyogenic granuloma occurring within a port-wine stain without a history of trauma or laser treatment in a man, and we contend that this occurrence offers unique insight into the pathogenesis of these poorly understood but commonly encountered entities.
Case Report
A 35-year-old Asian man with a history of a port-wine stain on his left upper back presented for evaluation of a "mushroom" growing within his birthmark (Figure 1). He noted that some lesion had been present in this location for several months but that it had grown rapidly in the previous 3 weeks and begun to bleed easily. There was no history of trauma or treatment of the area. On physical examination, the patient had a 1.4-cm pedunculated, moist tumor with a rough surface within a port-wine stain with surrounding contact dermatitis from the bandaging he had used to protect the friable papule. Saucerization was performed, and the extremely vascularized base was cauterized. Results of histopathologic examination revealed lobules of vascular hyperplasia consistent with pyogenic granuloma (Figure 2). Vascular ectasia was seen below the pyogenic granuloma that represented the underling port-wine stain.
Comment
The Table documents the reported cases of pyogenic granulomas arising within port-wine stains.3,10,11,13-23 Many have occurred after laser treatment of port-wine stains.11,15-17,24,25 Several cases have occurred after other manipulation of port-wine stains, such as grenz-ray therapy15 or local trauma.20 Three cases occurred during pregnancy, which is a hormonal state that is known to predispose the patient to the formation of pyogenic granulomas, including one patient who previously was treated with the 577-nm pulsed dye laser and subsequently became pregnant.14,15,21 Holloway et al18 noted the development of a proliferation that had a superficial component of pyogenic granuloma and a deeper component of cavernous hemangioma. Other authors have seen the occasional association of port-wine stains and cavernous hemangiomas.6 Not surprisingly, pyogenic granulomas have occurred within port-wine stains in the setting of other syndromes, such as phacomatosis pigmentovascularis and Sturge-Weber syndrome.19
Only rarely does the pyogenic granuloma seem to emerge from the port-wine stain without a history of manipulation or pregnancy, as it did in the present case. When there is no history of predisposing factors, the presentation can be very alarming, simulating other processes such as amelanotic melanoma.22,23 Interestingly, as opposed to the thickening and nodules that have shown to be more likely to develop in port-wine stains in the distribution of the trigeminal nerve, most of the pyogenic granulomas that have arisen in port-wine stains did so outside of this distribution, occurring more often on the neck, trunk, or extremities.
Clearly, the co-occurrence of these 2 vascular abnormalities must offer some information on the pathogenesis of these poorly understood conditions. Several years ago, Swerlick and Cooper10 speculated that the co-occurrence supported the possibility of pyogenic granulomas developing at the sites of microscopic arteriovenous anastomoses. More recently, as discussed by Garzon et al,9 a number of studies indicate that abnormalities in embryonic vasculogenesis are involved in forming vascular malformations such as port-wine stains, and these same abnormalities may predispose patients toward forming vascular hyperplasia or tumors. The well-known hormonally driven vascular changes that happen during pregnancy also may be able to generate pyogenic granulomas in the setting of port-wine stains.21
On a basic science level, chemical mediators such as inducible nitric oxide synthase have been implicated in the formation of pyogenic granulomas, and mast cells have been found to be dramatically increased in the settings of both pyogenic granulomas and port-wine stains, though this may not be evidence of a cause-and-effect relationship.26,27 With regard to laser-induced pyogenic granulomas in port-wine stains, speculation has involved several factors including local tissue trauma in an area of increased microscopic arteriovenous anastomoses, retention of abnormal vasculature, and nonspecific laser interaction with tissue.15,16
Pyogenic granulomas tend to develop on the fingers, lips, face, and hands (places known to be rich in arteriovenous anastomoses), suggesting that this vascular phenomenon tends to occur with minor trauma in the setting of such anastomoses.13,20 This conclusion is consistent with the available data. The present case of a pyogenic granuloma arising without recognized trauma in a port-wine stain also supports this hypothesis.
Conclusion