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Background: The worldwide outbreak of monkeypox has evidenced the usefulness of the dermatologic manifestations for its diagnosis., Objective: To describe the histopathologic and immunohistochemical findings of monkeypox cutaneous lesions., Methods: This is a retrospective histopathologic and immunohistochemical study of 20 patients with positive Monkeypox virus DNA polymerase chain reaction and immunohistochemical positivity for Vaccinia virus in cutaneous lesions. Four cases were also examined by electron microscopy., Results: The most characteristic histopathologic findings consisted of full-thickness epidermal necrosis with hyperplasia and keratinocytic ballooning at the edges. In some cases, the outer root sheath of the hair follicle and the sebaceous gland epithelium were affected. Intraepithelial cytoplasmic inclusion bodies and scattered multinucleated keratinocytes were occasionally found. Immunohistochemically, strong positivity with anti-Vaccinia virus antibody was seen in the cytoplasm of ballooned keratinocytes. Electron microscopy study demonstrated numerous viral particles of monkeypox in affected keratinocytes., Limitations: Small sample size. Electron microscopic study was only performed in 4 cases., Conclusion: Epidermal necrosis and keratinocytic ballooning are the most constant histopathologic findings. Immunohistochemical positivity for Vaccinia virus was mostly detected in the cytoplasm of the ballooned keratinocytes. These findings support the usefulness of histopathologic and immunohistochemical studies of cutaneous lesions for diagnosis of monkeypox., Competing Interests: Conflicts of interest None disclosed., (Copyright © 2022 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Epidermal keratinization disorders comprise a heterogeneous group of skin diseases that share the common feature of abnormal epidermal maturation, often leading to a disturbed stratum corneum., Objective: To describe two cases of an unusual disorder of epidermal keratinization., Methods: The clinical features of two unrelated patients with a long-standing widespread cutaneous eruption are described. Histopathologic examination and immunohistochemical studies were performed on skin biopsy specimens., Results: The eruption was characterized by symmetric erythematous, flat, discrete papules with a polygonal shape and fine scaling. The papules covered most of the skin surface and, in some areas of the trunk, they were arranged along the lines of cleavage, parallel to the ribs. There was no facial, mucosal, nail, or palmoplantar involvement; the teeth and hair were normal. The first patient had a sister with an identical eruption, and a brother of the second patient was said to have similar skin lesions. Histopathology revealed well-demarcated areas of compact eosinophilic orthokeratotic hyperkeratosis overlying a slightly acanthotic epidermis. Lesional skin showed weaker immunoexpression for connexin 43 compared with normal skin., Limitations: Only two patients and one sibling were investigated., Conclusion: We propose the name "saurian papulosis" to describe this newly described clinicopathologic entity., (Copyright © 2011 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.)

Background: Histopathologic study of lesions of cutaneous mucormycosis usually shows suppurative granulomas involving the deep dermis and subcutaneous fat. Large, broad and non-septate fungal hyphae are easily identified within the necrotic areas., Objective: The main goal of our study is to describe the histopathologic features of 13 cases of cutaneo-mucous mucormycosis, which mimicked the findings of pancreatic and/or gouty panniculitis and discuss the histopathologic differential diagnosis among these 3 disorders., Methods: Histopathologic examination of sections stained with hematoxylin-eosin, periodic acid-Schiff (PAS), Gomori methenamine, and Grocott stains. All sections were examined under polarized light. One case was immunohistochemically studied with anti-BCG antibody., Results: Histopathologically, the most striking feature consisted of the presence of groups of necrotic adipocytes lacking nuclei and large cytoplasm with pale basophilic hue due to calcium salts deposition. In other areas, groups of necrotic adipocytes filled with radially oriented needle-shaped and slightly eosinophilic crystals were seen. These intracellular crystals were refractile under polarized light examination. Numerous thick-walled non-septate fungal hyphae scattered throughout the necrotic areas were also seen in all cases., Limitations: The study was limited to 13 cases., Conclusions: Histopathologic study of 13 cases of subcutaneous mucormycosis demonstrated features closely resembling those of pancreatic panniculitis and/or gouty panniculitis. Ghost adipocytes should be not considered as diagnostic of pancreatic panniculitis and necrotic adipocytes containing needle-shaped refractile crystals should be not interpreted as specific of gouty panniculitis., (Copyright © 2011 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.)

Background: Cribriform carcinoma is the histopathologic variant of cutaneous apocrine carcinoma characterized by interconnected solid aggregations of neoplastic cells that are punctuated by small round spaces., Objective: To describe the histopathologic and immunohistochemical characteristics of this under-recognized cutaneous adnexal neoplasm., Methods: Twenty-six cases of primary cutaneous cribriform apocrine carcinoma were clinically, histopathologically, and immunohistochemically studied., Results: Seven neoplasms arose in males and 19 in females. The median age of the patients was 47.8 years. The lower and upper limbs were the most frequent sites. Histopathologically, the neoplasms consisted of well-circumscribed dermal nodules composed of multiple, interconnected, solid aggregations of basophilic epithelial cells that were punctuated by small round spaces. Immunohistochemically, the neoplastic cells expressed immunoreactivity for MNF116, AE1/AE3, Cam 5.2, cytokeratin 7, carcinoembryonic antigen, and epithelial membrane antigen., Limitations: All specimens came from dermatopathology laboratories, and some inherent selection bias may exist., Conclusions: Primary cutaneous cribriform apocrine carcinoma is a distinctive but little-known variant of cutaneous apocrine carcinoma.