Granulomatous Changes Associated With Pigmented Purpuric Dermatosis

Our review revealed that GPPD lesions typically involve the lower extremities and usually are asymptomatic, with the exception of occasional pruritus. Additional lesions have been reported on the dorsal aspect of the hands, and 1 case noted exclusive involvement of the wrist.⁶ Lesions of GPPD can range in their clinical appearance. Three of 13 patients presented with purpuric papules and 2 had brown pigmentation with hemorrhagic papules^3,4,6; the remaining 8 patients had erythematous or brown macules, papules, or plaques.^5-7 The most commonly associated disease condition was hyperlipidemia, which was reported in 7 of 13 cases.^5-7 Additional reported comorbidities included meningioma, renal calculi, obesity, hypertension, diabetes mellitus, chronic obstructive pulmonary disease, hepatitis C virus, ulcerative colitis, thrombocytopenia, and hyperuricemia. Reported serologic abnormalities included a rare positive antinuclear antibody, rheumatoid factor, and cryoglobulins.^3,6 Therapeutic efficacy in the management of GPPD has not been well described; however, for the rare cases in which therapies were described, they were largely unsuccessful, with 1 patient exhibiting spontaneous improvement.^3,4

Granulomatous PPD also appears to exhibit a range of histologic findings. All cases of GPPD shared fundamental components, such as a brisk perivascular infiltrate accompanied by RBC extravasation with variable hemosiderin-laden macrophages and a granulomatous infiltrate. All of the reports we reviewed described an intimate association between these components, with the granulomas being essentially superimposed on typical PPD. As for other types of PPD, obvious vasculitis characterized by a vasculocentric inflammatory infiltrate and evidence of vascular injury, such as fibrinoid necrosis of the vessel wall, has not been described in GPPD.^3-7 Finally, histologic changes suggestive of a relationship with cutaneous T-cell lymphoma, cytologic atypia, and epidermotropism have been described for some forms of PPD but have not been described for GPPD.^3-8

Our case reports expand the histologic spectrum of GPPD. Although patient 3 exhibited a relatively intimate association of granulomas and PPD, 2 of our cases (patients 1 and 2) demonstrated a granulomatous infiltrate in the mid to deep dermis, which is separate from the more superficially situated lichenoid lymphohistiocytic infiltrate, RBC extravasation, and hemosiderin-laden macrophages noted in the papillary dermis. Considered along with the absence of an obvious clinicopathologic explanation for the granulomatous infiltrates (eg, polarizable material, infectious organisms, systemic disease), these 2 cases (patients 1 and 2) suggest a composite form of PPD that combines the lichenoid pattern of PPD of Gougerot and Blum with a deep granulomatous component of GPPD. The importance of this distinction lies in the potential for physicians to overlook this potentially informative histologic pattern if only a superficial biopsy is performed. The clinical relevance is unclear; however, in our experience, it has been challenging to treat this relatively small subset of patients who have exhibited a limited response to treatment with topical steroids, intralesional steroids, pulsed dye laser, and vitamin supplementation.

The cause of the granulomatous infiltrate in GPPD is poorly understood. Seven of 13 cases included in our review occurred in patients with a history of hyperlipidemia.^5-7 Some have postulated that the constellation of findings of GPPD in hyperlipidemic patients reflects an underlying vascular injury process induced by lipid deposition in the endothelial cells with subsequent RBC extravasation and a secondary granulomatous response to the lipid deposits.^6,7 However, given the occurrence of GPPD in patients without hyperlipidemia, other mechanisms also must be considered in the pathogenesis of GPPD, including a reaction to medications, systemic diseases, and infectious etiologies (eg, hepatitis B virus).^4,6 As additional cases are described in the literature, other unifying clinical etiologies for this histopathologic reaction pattern may emerge.

Conclusion

Granulomatous PPD may comprise an underrecognized variant of PPD in cases when only a superficial biopsy is evaluated. Clinicians and pathologists should be aware of this variant, and in refractory cases of PPD, deeper sampling may be warranted to identify granulomas.