PMC9729728_01
Imiquimod-induced pemphigus vulgaris. (A) Papules and nodules on erythematous base in seborrheic distribution. (B) Painful erosions on the lips. (C) Diagnosis of superficial variant of basal cell carcinoma made through histological analysis (scale bar: 100 mum). (D) Histological examination shows intraepidermal acantholytic blister with a suprabasal cleavage plane compatible with atypical pemphigus vulgaris (scale bar: 100 mum). (E) Direct immunofluorescence displayed a weak intercellular deposition of IgG (scale bar: 100 mum). (F) By IB on keratinocyte extracts a band of 170 kDa was obtained by IgG (case), the molecular weight marker and anti-Dsg1 control antibody confirm that reactivity involves an unknown antigen of 170 kDa. (G) IB on keratinocyte extracts shows that the 170 kDa band does not correspond to EGFR detected by a specific alpha-EGFR polyclonal antibody.
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F1
On clinical examination, the skin showed papules, nodules on erythematous base in a seborrheic distribution (Figure 1A). The erosions on the lips and mucous membrane lesions were painful (Figure 1B). The patient was being treated with Imiquimod for multiple superficial BCCs for 3 days before the onset of the lesions (Figure 1C). Histopathological examination showed an intraepidermal acantholytic blister compatible with PV (Figure 1D). IgG and C3 (Figure 1E). Indirect immunofluorescence (IIF) on a monkey esophagus substrate showed epithelial intercellular IgG with a 1:160 titer. Of note, Enzyme-linked immunosorbent assay (ELISA) was negative for both Dsg 1 and 3 (1.6 and 0.8 U/ml, respectively; negative, <14 U/ml; indeterminate, 14 to 20 for Dsg1 and negative < 7 U/ml; indeterminate, 7-20 for Dsg3) (MBL, Nagoya, Japan) instead, a 170 kDa band, obtained by IgG, was seen by immunoblotting (IB) with keratinocyte extracts (Figure 1F). Since epidermal growth factor receptor (EGFR) presents a molecular weight marker similar to the unknown antigen, we also performed an IB on keratinocyte extracts using an anti-EGFR antibody as control (Figure 1G).
Timeline with relevant data about onset, diagnosis, and therapy of atypical pemphigus vulgaris.
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F2
The findings of routine laboratory tests, chest radiography and abdominal computed tomography scan were within normal limits (Figure 2). After reaching clinical remission without therapy, the patient underwent regular follow-up visits and after 2 years did not develop any relapse (Figure 2).