Dermoscopic Findings and the Clinicopathologic Correlation of Pigmented Purpuric Dermatosis: A Retrospective Review of 60 Cases

Abstract

Background: Pigmented purpuric dermatosis (PPD) is known as a chronic recurrent eruption which usually presents with petechiae and pigmented macules on the lower extremities. Dermoscopy is a noninvasive diagnostic tool in identifying pigmented and vascular lesions, which can also be beneficial in the evaluation of PPD.

Objective: We aimed to analyze the common dermoscopic characteristics of PPD, and correlate those findings with the histopathologic features. Additionally, dermoscopic and pathological findings in this study population were compared with other similar studies from the literature review.

Methods: A retrospective analysis was performed using data of 60 patients who were diagnosed as PPD by skin biopsy and had dermoscopic examination. The pathologic analysis was performed by categorizing the pattern into lichenoid, perivascular, interface, and spongiotic subtype, and the dermoscopic assessment was performed by the three authors independently.

Results: In dermoscopy, 96.7% of the patients showed red globules and dots, followed by brownish patch, coppery-red pigmentation, and annular comma-like vessels. The pathologic pattern analysis revealed statistically significant association of lichenoid pattern with coppery red pigmentation, perivascular pattern with annular/comma-like vessels, and spongiosis pattern with reticular pigmented network and linear vessels. The interrater similarity test showed total kappa value of 0.811 which referred to "very good".

Conclusion: In this study, the prevalence of dermoscopic features in Asian PPD patients was identified, which was similar with previous studies. The dermoscopic-pathologic correlation was found in four dermoscopic features. We suggest that dermoscopic examination is helpful in clinical diagnosis and pathological prediction of PPD.

Keywords: Dermoscopy; Pathology, clinical; Pigmentation disorders; Pigmented purpuric dermatosis; Skin diseases, vascular.

Fig. 1. Clinical presentation and subtypes of pigmented purpuric dermatosis (PPD). The most commonly observed clinical subtype of PPD was Schamberg disease (A), showing cayenne-pepper like pigmentation. (B) Majocchi purpura has peripheral light erythematous-brown patches with peripheral extension. (C) Lichen aureus shows multiple lichenoid papules. (D) PPD of Gougerot–Blum shows lichenoid papules and plaques of erythematous-brown pigmentation. In patients with eczematid-like purpura of Doucas-Kapetanakis (E), pruritic eczematous patches are observed.

Fig. 2. Three most common dermoscopic features of pigmented purpuric dermatosis. Red globules and dots (black arrowheads) were most prevalently observed as (A) and (B). Brownish patches (black asterisks) were seen as (C) and (D). Coppery red pigmentation (white asterisks) revealed as bright orange-brown colored patches in the polarized images as such in (E) and (F).

Fig. 3. Other main dermoscopic features of pigmented purpuric dermatosis. Annular vessels and comma-like vessels (black arrowheads) were observed as (A), and some linear vessels (black arrows) were also seen as (F). Distinguished from brownish patch or coppery red pigmentation, there were reticular brownish networks (black asterisks) as such in (B), (C), and (F), resembling the dermoscopic image of solar lentigines. Red patches (white asterisks) and brown dots (white arrowheads) were also noted as (D) and (E).

Fig. 4. Histopathologic images of the lichenoid, perivascular, and interface pattern patients. (A, D) In lichenoid pattern, there were dense band like lichenoid infiltration of lymphocytes in the upper dermis. Epidermal change of focal hyperkeratosis, erythrocyte extravasation, lymphocyte exocytosis and hemosiderin deposition was identified. (B, E) Perivascular pattern showed focal vacuolization in the basal layer, erythrocyte extravasation, lymphocyte exocytosis. Perivascular lymphocyte infiltration in the papillary dermis was also identified. (C, F) There was significant basal layer vacuolization with focal basal/dermal pigmentation and dyskeratotic keratinocytes in interface pattern patient. H&E, ×40 (A~C); ×200 (D~F) magnification images.