Abstract This article will address the main aspects of skin manifestations associated with COVID-19, based on a review of the literature published to date. Since the beginning of the pandemic, more than 1,500 articles have been published on the subject. Regarding the pathophysiology, it is believed that the same mechanisms responsible for the disease in the main target organs also act in the skin, although they are not yet fully elucidated. The actual frequency of dermatological manifestations remains uncertain - it can range from 0.2% to 45%, being close to 6% in systematic reviews. Pioneering studies of large case series conducted in European countries and the USA provide the first information on the main skin manifestations associated with COVID-19 and propose classifications regarding their clinical presentation, pathophysiology, as well as their frequencies. Although there is yet no consensus, maculopapular eruptions are considered the most frequent presentations, followed by erythema pernio-like (EPL) lesions. Manifestations such as urticaria, vesicular conditions and livedo/purpura/necrosis are rare. The time of onset, severity, need for specific treatment and prognosis vary according to the clinical presentation pattern. The increasing histopathological description of skin conditions can contribute to the diagnosis, as well as to the understanding of the pathophysiology. Also, in the dermatological field, the relationship between COVID-19 and androgens has been increasingly studied. Despite all the generated knowledge, the actual biological meaning of skin manifestations remains uncertain. Therefore, the exclusion of the main differential diagnoses is essential for the correlation between skin manifestation and COVID-19.

Abstract Lymphocytic thrombophilic arteritis is a recently described entity, histopathologically characterized by lymphocytic vasculitis that affects the arterioles of the dermo-hypodermic junction, associated with deposition of fibrin and a luminal fibrin ring. A 49-year-old female patient presented with achromic maculae and a well-defined ulcer on the medial aspect of the left lower limb. The biopsy showed intense inflammatory infiltrate in the papillary dermis with a predominance of lymphocytes, and medium-caliber vessels surrounded by mononuclear infiltrates in the deep reticular dermis. Masson’s trichrome staining showed intense destruction of the muscle layer of the vascular wall and a fibrin ring. Good clinical response was attained with azathioprine. The authors believe that the ulceration might be another clinical presentation or represent an atypical progression of this condition.

Abstract Protothecosis is a rare condition caused by the aclorophylated algae of the genus Prototheca. In humans, protothecosis, caused mainly by P. wickerhamii, manifests itself in three forms: cutaneous, articular and systemic. It can occur in both immunocompetent and immunosuppressed individuals, being much more common in the latter. We present a new case of protothecosis in Brazil in a kidney transplant recipient.

Abstract: Pemphigus vulgaris is a chronic autoimmune bullous dermatosis that results from the production of autoantibodies against desmogleins 1 and 3. It is the most frequent and most severe form of pemphigus, occurring universally, usually between 40 and 60 years of age. It usually begins with blisters and erosions on the oral mucosa, followed by lesions on other mucous membranes and flaccid blisters on the skin, which can be disseminated. There is a clinical variant, pemphigus vegetans, which is characterized by the presence of vegetating lesions in the large folds of the skin. Clinical suspicion can be confirmed by cytological examination, histopathological examination, and direct and indirect immunofluorescence tests. The treatment is performed with systemic corticosteroids, and immunosuppressive drugs may be associated, among them azathioprine and mycophenolate mofetil. More severe cases may benefit from corticosteroids in the form of intravenous pulse therapy, and recent studies have shown a beneficial effect of rituximab, an anti-CD20 immunobiological drug. It is a chronic disease with mortality around 10%, and septicemia is the main cause of death. Patients need long-term and multidisciplinary follow-up.

Abstract: Background: Diseases caused by melanized fungi include mycetoma, chromoblastomycosis and phaeohyphomycosis. This broad clinical spectrum depends on the dynamic interactions between etiologic agent and host. The immune status of the host influences on the development of the disease, as, an exemple. phaeohyphomicosis is more frequently observed in immunocompromised patients. Objectives: Examine the histological inflammatory response induced by Fonsecaea pedrosoi in several different strains of mice (BALB/c, C57BL/6, Nude and SCID, and reconstituted Nude). Methods: Fonsecaea pedrosoi was cultivated on agar gel and a fragment of this gel was implanted subcutaneously in the abdominal region of female adult mice. After infection has been obtained, tissue fragment was studied histopathologically. Results: There were significant changes across the strains, with the nodular lesion more persistent in Nude and SCID mice, whereas in immunocompetent mice the lesion progressed to ulceration and healing. The histopathological analysis showed a significant acute inflammatory reaction which consisted mainly of neutrophils in the initial phase that was subsequently followed by a tuberculoid type granuloma in immunocompetent mice. Study limitations: There is no a suitable animal model for chromoblastomycosis. Conclusions: The neutrophilic infiltration had an important role in the containment of infection to prevent fungal spreading, including in immunodeficient mice. The fungal elimination was dependent on T lymphocytes. The re-exposure of C57BL/6 mice to Fonsecaea pedrosoi caused a delay in resolving the infection, and appearance of muriform cells, which may indicate that re-exposure to fungi, might lead to chronicity of infection.

Abstract: Fusariosis is due to inhalation or direct contact with conidia. Clinical presentation depends on host's immunity and can be localized, focally invasive or disseminated. Given the severity of this infection and the possibility for the dermatologist to make an early diagnosis, we report six cases of patients with hematologic malignancies, who developed febrile neutropenia an skin lesions suggestive of cutaneous fusariosis. All patients had skin cultures showing growth of Fusarium solani complex, and they received amphotericin B and voriconazole. As this infection can quickly lead to death, dermatologists play a crucial role in diagnosing this disease.

Abstract: Linear immunoglobulin A bullous dermatosis is a rare autoimmune disease that usually has an excellent prognosis in childhood; however, its control is more difficult in adults. It presents heterogeneous clinical manifestations and is frequently confused with other bullous diseases such as bullous pemphigoid and Duhring’s dermatitis herpetiformis. Dermatologists’ awareness of this disease contributes to early diagnosis and appropriate treatment. We thus report three cases of linear immunoglobulin A dermatosis in adults.

Abstract: Lupus erythemathosus is a chronic, relapsing disease with acute, subacute, and chronic lesions. Effluvium telogen occurs in the setting of systemic activity of the disease, and cicatricial alopecia results from discoid lesionsin on the scalp. Other types of alopecia, like alopecia areata, may rarely be found in lupus. Frontal fibrosing alopecia is characterized by frontotemporal hairline recession and eybrow loss. Histophatologically, it cannot be differentiated from lichen planopilaris.It is controversial whether frontal fibrosing alopecia is a subtype of lichen planopilaris.. A pacient with chronic lichenoid lupus erythematosus is described with clinical, histophatological and dermoscopic features of frontal fibrosing alopecia.We have not been able to find in the literature cases of frontal fibrosing alopecia as a clinical manifestation of lupus.

Abstract: Liposarcomas correspond to the most common histological subtype of soft tissue sarcomas. They can be subdivided into: well differentiated or atypical lipoma, undifferentiated, myxoid, round, and pleomorphic cells. Atypical lipomas are the most prevalent and usually appear as asymptomatic softened tumors. They are locally aggressive but rarely lead to distant metastases. The diagnosis of this tumor is based on the imaging and histopathologic findings. Treatment consists of excision surgery with complete tumor removal. It has a good prognosis due to the low percentage of distant metastases. We report a rare case of giant atypical lipoma as well as the adopted therapy and evolution.

ABSTRACT Pigmented Bowen's disease is a rare subtype of Bowen's disease. Clinically it presents as a slow-growing, well-defined, hyperpigmented plaque, and should be included as a differential diagnosis of other pigmented lesions. The authors describe a challenging case of pigmented Bowen's disease with non-diagnostic dermscopy findings.

Abstract Cryptococcosis is a common fungal infection in immunocompromised patients, caused by genus Cryptococcus, presenting with meningitis, pneumonia, and skin lesions. Cutaneous presentation can be varied, but specifically in solid organ transplant recipients (iatrogenically immunocompromised), cryptococcosis should always be considered in the differential diagnosis of cellulitis-like lesions, since the delay in diagnosis leads to worse prognosis and fatal outcome. We report four cases of cryptococcosis with cutaneous manifestation not only for its rarity, but also to emphasize the important role of the dermatologist in the diagnosis of this disease.