The term “pyogenic granuloma” or “granuloma pyogenicum,” which is a relic of 19th century medicine, is a misnomer.¹,²,⁶,⁹,¹⁰ Because the inflammatory component is prominent, early pathologists erroneously implicated pyogenic bacteria. There is no bacterial infection or purulent inflammatory exudate involved, which belies the “pyogenic” prefix. Nor are epithelioid or giant cells observed, which negates that “granuloma” formation is involved in the histogenesis.⁹,¹⁰

The exact pathogenetic sequence of events underlying the development of PG on the eyelid is not well understood, but the quintessential event is an injury to the conjunctival epithelium,⁶,⁷,⁹,¹⁰ particularly in the setting of a transverse conjunctival wound that transects the meibomian gland orifices, which may continue to express meibomian secretions for a few days hampering epithelial healing.⁶,¹⁰ Alternatively, the presence of an exogenous agent like the sharp edge of a Jones Pyrex tube would also inhibit conjunctival healing and could result in the development of PG.¹⁰ The older theory that a pyogenic granuloma is a reaction to foreign material is unlikely.¹⁰,¹²,¹³

Pyogenic granulomas may be classified as a primary (idiopathic) type or secondary to an insulting factor.⁹ Primary lesions may appear de novo without any apparent cause⁹; however, this is an uncommon presentation. More commonly, pyogenic granulomas develop on top of preexisting chalazia even without a history of chalazion excision, due to minor trauma to the periocular region, or at the surgical site following chalazion excision. Other scenarios include the development of PG following transconjunctival surgical approaches to the orbital floor and transconjunctival blepharoplasty.⁶,⁷,⁹,¹⁰ Other surgical procedures that may also be associated with the development of PG on the bulbar conjunctiva include strabismus surgery and scleral buckling, pterygium, or stent-related trauma with dacryocystorhinostomy surgery.⁹,¹⁰,¹⁴,¹⁵,¹⁶

Recently, BRAF and RAS mutations have been demonstrated in patients with secondary PG occurring on top of port wine stains.¹⁷,¹⁸,¹⁹ BRAF and RAS drive angiogenesis by enhancing the expression of several proangiogenic and proinflammatory molecules.¹⁷,¹⁸ Recent evidence also suggests that a viral etiology (herpesvirus type 1, Orf virus, and/or human papillomavirus type 2) may also be implicated.¹⁹

Pyogenic granulomas can occur at any age or sex, but they have a predilection for male children and young adults.¹⁸ A history of a prior insult such as surgery or trauma is usually elicited from the patient, and in cases where PG develops after chalazion excision, this may be interpreted by the patient as recurrence of the lesion. The patient should specifically be asked about a history of remote surgical procedures, particularly scleral buckling.⁶,¹⁰

Even when the patient denies any antecedent history, a ruptured chalazion, the presence of which may be unknown to the patient, can sometimes be felt as a palpable eyelid mass adjacent to the pyogenic granuloma upon clinical examination. Pyogenic granuloma is usually confined to the palpebral or bulbar conjunctiva. Rarely it may develop on the lid margin or the outer surface of the eyelid. It usually grows rapidly in the days to weeks after a conjunctival injury from surgery or trauma.⁴ Typically, the new lesion starts as a small lump on the palpebral conjunctiva, progressively increasing in size, and may even protrude from the eyelids.⁴ The shape of the lesion is variable from patient to patient.⁹ It may rarely present as a sessile, broad-based lesion but more commonly presents as a pedunculated lesion with an underlying stalk of connective tissue and feeder blood vessels (Figure 107.1).⁷ Lifting the tip of the granuloma off the surface of the conjunctiva usually demonstrates the peduncle.⁹ Pyogenic granulomas are usually reddish and of friable consistency that may bleed on the slightest touch or even spontaneously because they receive florid blood supply from the conjunctive.⁴,⁶,⁷,⁹