Sir,

Foliaceus pemphigus is an intraepidermal autoimmune bullous disease characterized by the presence of circulating antibodies against desmoglein-1 found in the granular layer of the epidermis.

The clinical presentation of foliaceus pemphigus is quite well described and typical, and it involves the development of superficial erosions with scaling and crusting in the seborrheic areas: scalp, face, chest, and upper back. Nevertheless, it is known for its clinical polymorphism.

Erythema gyratum repens (EGR) is a rare cutaneous eruption characterized by concentric erythematous moving bands forming a wood-grain appearance. It is considered to be a paraneoplastic eruption. Rongioletti et al. reported that 70% of cases are related to an underlying neoplasm, yet some cases are related to benign diseases [1].

Some dermatoses may mimic EGR and, therefore, may be called EGR-like eruptions.

Herein, we report the case of a superficial pemphigus with a particularly spectacular presentation.

A 68-year-old male, without any medical history or chronic medication, presented with erosions and scaly, crusty erythematous patches initially located on the back and arms, subsequently extending to the buttocks and inner thighs, without any blisters seen. Furthermore, there was no mucosal involvement.

On the fourth day of his hospitalization at our department, a physical examination revealed new plaques arranged on erythematous, annular lesions forming a concentric ring on the back expanding centrifugally, suggesting erythema gyratum repens (Fig. 1). The Nikolsky test was positive.

Figure 1: Clinical photograph of the annular erythematous lesions suggesting erythema gyratum repens.

Skin histology showed acantholysis with subcorneal blistering. Direct immunofluorescence revealed intercellular IgG/C3 deposition in the epidermis (Figs. 2a and 2b) with a honeycomb fluorescence pattern. A whole blood workup was done, including tumor markers. CT scan, anti-BP180, anti-BP230, were all negative. Circulating intercellular antibodies by indirect immunofluorescence were positive. The final diagnosis of foliaceus pemphigus was, therefore, established.

Figure 2: (a and b) A biopsy from the back showing separation within the granular cell layer with few acantholytic cells and a perilesional biopsy from the back showing IgG deposits in the intercellular spaces.

Treatment with prednisone (1.5 mg/kg/day) and dapsone 100 mg/day was initiated along with daily showers and bandages to avoid infection. The eruption cleared completely in three months.

The diagnosis of foliaceus pemphigus was made on clinical features (exfoliative dermatitis made with erythematous scaly patches and erosions, the absence of tense blisters, and genital or oral involvement) and histopathological, autoimmune analysis.

Our patient had an atypical clinical presentation with EGR features. The annular arrangement of plaques or blisters with an EGR-like eruption is reported in very few cases of bullous dermatosis such as bullous pemphigoid [2], bullous lupus erythematous [3], linear IGA dermatosis [4], anti p-200 pemphigoid [1], yet no case of an EGR-like pemphigus foliaceus has ever been published to our knowledge.

It is also important to note that a unique clinical pattern may occur in children, with individual lesions appearing as arcuate, circinate, or polycyclic [5]. The reason why these different dermatoses may have clinically similar features is unknown. The presence of EGR-like eruptions during bullous dermatoses might reflect similar autoimmune mechanisms. Although histological findings in EGR are not specific and physiopathology remains to be elucidated, there is evidence of activated immunological mechanisms in EGR. In particular, IgG and C3 deposits at the basement membrane zone have been reported [6,7].

In our case, the negativity of paraclinical tests in search of associated malignancy and the quick response to dapsone and corticosteroids were sufficient to exclude an authentic EGR.

The diagnosis of paraneoplastic pemphigus was considered as well based on the atypical clinical features yet was also ruled out thanks to the histopathology that did not show any dyskeratosis or lichenoid interface dermatitis without forgetting the negativity of the tests in search of a malignancy.

To conclude, we report an atypical clinical presentation of foliaceus pemphigus with an EGR pattern, successfully treated by corticosteroids and dapsone. Our case illustrated the heterogeneous clinical presentation of pemphigus foliaceus.

REFERENCES

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2.Grilletta EA, Ellis DL. Paraneoplastic bullous pemphigoid presenting with erythema gyratum repens-like figurate erythema. JAAD Case Rep. 2021;12:37-9.

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