Figure 1. Case 1. Brown, round, sharply demarcated plaques on the leg.
Figure 2. Case 1. A, Under dermoscopy, the broad brown band is visible in the periphery with white rims along the inside and outside of the band. The fine pigment network, dots and/or globules, and the small shining white spots in the brown band are also visible. B, With the furrow ink test, pores are visible in the peripheral brown area (arrows) as is the fine texture in the central portion of the lesion (asterisk).
Figure 3. Furrow ink test in case 1. Large pores are seen at regular intervals, some of which correspond to hairs (arrows).
Figure 4. Pathologic findings in case 1 (hematoxylin-eosin, original magnification ×40). Visible are the cornoid lamella (asterisk) and cornoid plugs corresponding to a hair (white arrow) and a sweat pore (black arrow).
Uhara H, Kamijo F, Okuyama R, Saida T. Open Pores With Plugs in Porokeratosis Clearly Visualized With the Dermoscopic Furrow Ink Test: Report of 3 Cases. Arch Dermatol. 2011;147(7):866-868. doi:10.1001/archdermatol.2011.174
Author Affiliations: Department of Dermatology, Shinshu University School of Medicine, Matsumoto, Japan.
Porokeratosis is an autosomal dominantly inherited disorder characterized by brown annular lesions with scaling ridges, which histopathologically corresponds to the cornoid lamella. Several dermoscopic findings of porokeratosis have been reported, including a whitish peripheral rim, brown globules and/or dots, red dots and/or red lines, and scarlike structures in the center of the lesions.1 Herein, we report 3 cases of porokeratosis of Mibelli dermoscopically clearly showing multiple pores.
An 88-year-old man presented with a 30-year history of multiple brown plaques. No family history of porokeratosis was reported. Clinical examination revealed that brown, round, sharply demarcated annular plaques up to 3 cm in size were widespread on the trunk and extremities (Figure 1). Dermoscopic evaluation of the lesions showed a brown rim along on periphery of the lesions (Figure 2A). The fine pigment network, dots and/or globules, and the small shining white or brown spots were mainly observed within the brown band.
Staining of the skin surface with whiteboard marker (the furrow ink test) clearly revealed the rims along the inside and outside of the peripheral band and multiple open pores with keratotic plugs (Figure 2B). Furthermore, the furrow ink test highlighted the differences in texture on the skin surface in some lesions. The texture was diminished and flattened in the periphery and finer in the central portion of the lesions compared with normal skin. Some pores corresponded to hair openings, which were confirmed pathologically (Figure 3 and Figure 4). Although the pores were observed in almost all lesions, the number and distribution varied in each lesion.
An 89-year-old man presented with a 2-year history of multiple brown plaques. Clinical examination revealed brown, sharply demarcated annular plaques up to 2 cm in size on the extremities. Dermoscopically, the multiple small brown spots were observed in the central area. Pathologic findings showed a column of compact hyperkeratosis with parakeratosis in the part corresponding to acrosyringium as well as typical cornoid lamella in the periphery of the lesion.
A 52-year-old man presented with a 1-year history of multiple brown plaques. Clinical examination revealed light-brown, round, sharply demarcated plaques on the extremities. Dermoscopic findings were similar to those in cases 1 and 2, except with fewer pores.
Dermoscopic examination in our cases showed that the multiple pores seemed to correspond to hair openings and sweat pores. Porokeratosis of Mibelli was originally believed to involve columns of parakeratosis, the cornoid lamella, emerging only from the ostia of eccrine ducts. However, Reed and Leone2 later proposed that the cornoid lamella did not originate from the ostia of eccrine ducts and that porokeratosis was a clonal disease of the epidermal keratinocytes. However, in actuality, the cornoid lamellae seem to be associated with appendages. Reed and Leone2 also reported that cornoid lamellae was observed in hair follicles in the center of the lesions in 18 of 35 cases and sweat ducts in 4 of 35 cases. Recently, Minami-Hori et al3 reported that the cornoid lamella was observed in the follicular infundibulum in about half of 73 cases and in the acrosyringium in one-third of 73 cases, without any regard to the subtype. They proposed that there might be putative stem cells of the appendages on the portion lower than the follicular infundibulum and acrosyringium if cornoid lamellae are assumed to be formed at the boundary between normal and abnormal clones.
In this study, the staining by whiteboard marker, or furrow ink test, clearly revealed the peripheral rim, open pores, and surface textures. These findings seem to reflect pathologic changes in the epidermis during each inflammatory phase. The whiteboard marker pen used in this study contains colorants, alcohol, and binder resin. Once this combination is transferred to a whiteboard, the alcohol evaporates, leaving the binder resin and colorant as a friable film loosely adhering to the board. It can therefore be removed easily from the smooth surface, but it adheres to any scratches on the surface. This characteristic is appropriate for our purpose, which is staining only the furrows of the skin.4 The furrow ink test was first reported as a method that helped distinguish the pigmented lesions on acral volar skin.4,5 This method could be an additional tool for the dermoscopic diagnosis of skin disorders that involve changes in skin texture.
Correspondence: Dr Uhara, Department of Dermatology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan (firstname.lastname@example.org).
Accepted for Publication: December 3, 2010.
Author Contributions: Dr Uhara had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Uhara. Acquisition of data: Uhara and Kamijo. Analysis and interpretation of data: Uhara, Okuyama, and Saida. Drafting of the manuscript: Uhara and Saida. Critical revision of the manuscript for important intellectual content: Uhara, Kamijo, Okuyama, and Saida. Statistical analysis: Uhara. Obtained funding: Uhara. Administrative, technical, and material support: Uhara and Kamijo. Study supervision: Uhara, Okuyama, and Saida.
Financial Disclosure:: None reported.