Bullae autoimmune diseases can be induced by environmental factors in a genetically susceptible individual, and viruses may be important triggers for this process. Coronavirus disease 2019 (COVID-19) is a multisystemic disease known for developing many types of skin lesions. However, little is known about post-COVID-19 manifestations. A previous healthy male patient, 43 years old, with resistant mediastinal Hodgkin's lymphoma stage II diagnosed in 2019, without treatment at the moment, developed monomorphic flaccid bullae on the trunk 40 days after testing positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although he had risk factors for IgA and paraneoplastic pemphigus, there were no elements for these diseases. The investigation confirmed a pemphigus vulgaris (PV). PV had a good response to treatment with prednisolone 1 mg/kg per day, and methotrexate 15 mg subcutaneously was added per week. The patient was discharged with oral methotrexate and prednisolone at the same dose. Prednisolone was decreased by 20 mg per day during the follow-up. Viruses such as herpesvirus, cytomegalovirus, and varicela zoster can act as triggers for PV. This process is not immediate after the infection because it depends on the change in antibodies initially produced against the virus that start to identify antigens present in the skin's anchoring structures. SARS-CoV-2 can induce autoimmunity, as seen in Guillán-Barré syndrome and in Kawasaki disease. It is a highly immunogenic virus that is the perfect agent for triggering PV. This case can be considered a cutaneous autoimmune post-COVID-19 manifestation.

Human sporotrichosis is an emerging disease caused by fungi of the genus Sporothrix, distributed worldwide, but mostly in tropical and subtropical regions. This disease is caused by traumatic inoculation of contaminated material (either animal or vegetal in origin) into the skin. Sporotrichosis cases caused by zoonotic transmission through felines have significantly increased over the last 20 years in Brazil. There is a spectrum of clinical outcomes, from classical lymphocutaneous and fixed forms to disseminated manifestations and extracutaneous lesions; however, hypersensitivity reactions related to sporotrichosis, including Sweet syndrome (acute febrile neutrophilic dermatoses), are uncommon. In Brazil, Sporothrix brasiliensis is repeatedly associated with feline infection and has consistently shown higher virulence, tendency to escalate to outbreaks or epidemics, and development of atypical forms. Therefore, the objective of the present study was to report the cases of 10 patients with sporotrichosis infected by S. brasiliensis species who developed Sweet syndrome to alert this association, especially in endemic areas.

Atypical and unusual locations of psoriasis are very frequent. However, localized linear psoriasis is rare, with few cases described in the literature. It is characterized by a linear distribution of psoriasis lesions along Blaschko lines. We report the case of a three years old child, who presented unilateral erythematous scaly plaques arranged along Blaschko lines in the left hemithorax, with no associated symptoms and no lesions in other parts of the body. The differentiation of linear psoriasis from other linear dermatoses is not easy. The combination of a thorough history, a careful examination of the skin and histopathology are essential to ensure the correct diagnosis and appropriate treatment.

Chronic cutaneous lupus erythematosus in a linear configuration is rare, particularly in children, demonstrating similar incidence in both genders, no photo-sensitivity and lower probability of progression to systemic disease. We describe the case of a 9-year-old girl who presented erythematous papules with central atrophy on the upper and lower right limbs, asymptomatic and following the lines of Blaschko, since age four. Histological examination showed atrophy of the epidermis with aggression from epidermal-dermal interface and periadnexal and perivascular lymphocytic inflammatory infiltrate. Laboratory tests showed ANA in a titer of 1:320, in a dense and fine speckled pattern. Due to the rarity of presentation and location of the disease, this case is reported here.