Dermoscopy of Post-pemphigus Acanthoma: A Case Report

Dear Editor, Post-pemphigus acanthoma (PPA) is an uncommon condition that develops at the sites of previous bullae that are in remission in pemphigus vulgaris or pemphigus foliaceus. It is characterized by well-defined plaques with verrucous surfaces. Epidermal hyperproliferation due to special autoantibodies released by bacteria is implicated in the pathogens.[1] The close differentials are seborrheic keratosis (SK), squamous cell carcinoma (SCC), Hailey–Hailey disease (HHD) clinically, and acantholytic acanthoma histologically.[2] Diagnosis is by characteristic histopathology and immunofluorescence. Here, we report a case of PPA in a patient of pemphigus vulgaris, with its dermoscopic features. A 23-year-old male previously diagnosed with pemphigus vulgaris for 18 months had received two doses of 1 g rituximab infusion twice 15 days apart and topical corticosteroids. He was under remission for 3 months. He came with multiple, non-itchy, hyperkeratotic plaques over the trunk and shoulders for the past 1 month. The lesions were present at the site where he previously had bullae/erosions. At the time of presentation, he had no active bullae or erosions. The lesions started as erythematous papules which ultimately modified to hyperkeratotic plaques with an erythematous base. Cutaneous examination shown multiple hyperkeratotic plaques with verrucous surface on an erythematous base distributed over the anterior, posterior trunk, and shoulders, and the lesions were not associated with pain or discharge. The average size of lesions was 1 cm, with the largest being 2 cm and the smallest being 0.5 cm. Scalp and mucosae were spared [Figure 1a]. SK, SCC, and nonintertriginous HHD were considered for diagnosis.Figure 1: Clinical image of postpemphigus acanthoma shows well-defined, eroded, and crusted plaques on the back (a) Dermoscopy from white box shows white areas (yellow star), white lines (yellow lines), and scales (red arrow) with brown-pigmented areas (black star), black dots (red circle), and broken hairs (yellow circle) on a pinkish background (b) Illuco IDS 1100, polarized, ×10Dermoscopy of the plaque showed white areas in the center; brown and gray globules, white lines, and scales on the pinkish background. Few broken hairs and black dots were noted [Figure 1b]. The dermoscopy from crusted lesions exhibited polygonal white-gray and brown clods in a cobblestone pattern on pink background. Each polygon was studded with numerous black-to-brown dots, and few dotted vessels were seen [Figure 2a and b]. Histopathology from verrucous lesion revealed hyperkeratosis, acanthosis, papillomatosis, acantholysis, and cleft formation at the suprabasal level. Follicular involvement and dermal melanophages were found in addition to villi formation at a few locations [Figure 3a and b]. We could not do immunofluorescence and antidesmoglein antibody titer due to lack of facilities.Figure 2: Dermoscopy from yellow box (in clinical image) shows polygonal white-gray (white star) and brown (white arrow) area in a cobblestone pattern with brown dots on each clod (white circle). Note the pinkish background (yellow star) (a) White-gray (yellow star) area with black-to-brown dots on each clod (yellow circles) and dotted vessels (yellow arrow) on pinkish background (b) Illuco IDS 1100, polarized, ×10Figure 3: Histopathology shows hyperkeratosis (black arrow), acantholysis (green arrows) and the formation of suprabasal clefts with dermal melanin (black circle) and follicular involvement (white arrow) (a) H and E, ×100. Acanthosis and focal hypergranulosis (white star), suprabasal cleft (green arrow), and acantholytic cells (solid black arrow) with retained melanin in the epidermis (green circle) are noted (b) H and E, ×400Diagnosis of PPA was established on the basis of history, clinical features, and histopathology. He was started with deflazacort 30 mg in tapering doses and topical clobetasol propionate 0.05%, twice a day application. Lesions started to resolve with postinflammatory hyperpigmented patches [Figure 4a]. Dermoscopy demonstrated cobblestone arrangement of translucent, circular, and oval fashion pigmented structures which are separated by white lines on subtle pink background [Figure 4b and c].Figure 4: Clinical image of postpemphigus acanthoma after treatment shows postinflammatroy brown patches (a) Dermoscopy shows brown circular to oval penny-like structures (red box) in a cobblestone arrangement. White lines (red arrow) are noted separating brown structures. Inset; close-up view showing each penny-like structure has central white dots representing either eccrine or follicular opening (b) Brown circular to oval penny-like structures (yellow box) in a cobblestone arrangement with white lines (red arrow) separating brown structures are noted (c) Illuco IDS 1100, polarized, ×10There is a sparsity of descriptions of PPA in literature. A case series by Yesudian et al. described PPA in 13 patients among 52 pemphigus vulgaris and pemphigus foliaceus patients.[1] It develops on previously healed lesions and may manifest as single plaque[2] or multiple crusted lesions.[3] This implies that physicians should have a high index of suspicion when verrucous lesions appear on the sites of previously healed bullae in pemphigus vulgaris. However, dermoscopic reports of PPA are lacking in the dermoscopic literature. In this study, plaques showed brown and gray clods corresponding to epidermal and dermal melanin, respectively. White areas, scales, and white lines are due to acanthosis, hyperkeratosis, and depigmented tips of dermal papillae, respectively. Dotted vessels are due to dilated capillaries in the papillary dermis. Follicular involvement resulted in hair changes. Nonintertriginous HHD, a close differential, demonstrates irregular pink areas surrounded by white cloud-like structures that appear as crumpled fabric patterns and gray and brown areas in the periphery.[4] Vessels are seen in the form of uniform dotted vessels and nonuniform linear curved vessels.[5] Dermoscopy shows unique features in PPA and HHD as well; thus, it is useful as a valid diagnostic tool in the differentiation of both. Dermoscopy of crusted lesions showed white-gray polygonal clods with multiple brown dots on a pinkish background. White-gray polygonal clods represent extensive hyperkeratosis and brown-gray dots correlate with epidermal and dermal melanin, respectively. Giant SK reveals a parched appearance and moth-eaten borders with fissures and ridges. Vessels or milia-like cysts are not seen.[6] Thence, dermoscopy demonstrates different features in SK and PPA. Another important differential is SCC which shows white clods, white areas, white circles, white streaks, and white scales with monomorphic and polymorphic vessels.[7] Interestingly, healed lesions demonstrated translucent circular-to-oval-shaped brown pigment resembling “penny-like” structures which were arranged in a cobblestone pattern. A few circular pigmented structures were seen encircling the eccrine and follicular openings [Figure 4b]. These “penny-like” structures are akin to normal pigment networks. Here also, melanin in the horizontal arm and vertical arm of rete ridges produces a pale brown area in the center and dark brown rim, respectively. Nevertheless, they are not interconnected to appear as grid-like patterns. Furthermore, this observation should be speculated with valid studies. White lines were indicative of fibrotic areas after healing. Histopathological differentials include epidermolytic acanthoma which shows pronounced acanthosis and epidermolytic hyperkeratosis with speckled keratohyalin granules and epithelial eosinophilia.[8] While acantholytic acanthoma reveals hyperkeratosis, acanthosis, and papillomatosis.[9] In conclusion, dermoscopic features of PPA are definitive and assist in the distinction of close clinical differentials and features correlate well with histopathological changes as well. Observations are based on a single patient; further studies are recommended to validate these findings. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.