Amicrobial pustulosis of the folds: A case report of a rare variant of neutrophilic dermatosis associated with systemic lupus erythematosus.

Amicrobial pustulosis of the folds (APF) is a rare neutrophilic dermatosis found in association with autoimmune diseases. We present a 49-year-old woman with a history of systemic lupus erythematosus and a recurrent pustular eruption in the cutaneous folds. Histologic examination revealed spongiform pustulosis and dermal neutrophilic infiltrate.

Neutrophilic fixed drug eruption, a histopathologic variant or an expected finding?-A report of two cases and review of the literature.

Fixed drug eruption (FDE) is an adverse drug reaction characterized by recurrent circumscribed lesions at the same location upon re-exposure to the culprit medication, resulting in distinct postinflammatory hyperpigmentation. Histopathologically, FDE demonstrates a predominantly lymphocytic interface or lichenoid infiltrate with basal cell vacuolar changes and keratinocyte dyskeratosis/apoptosis. The term "neutrophilic fixed drug eruption" has been used to describe cases in which the inflammatory infiltrate is predominantly neutrophilic.

Reactive infectious mucocutaneous eruption due to COVID-19 with erythema-multiforme-like lesions and myeloid cells.

Reactive infectious mucocutaneous eruption (RIME) is a recently described entity in which there is prominent mucositis, most commonly involving the oral and urogenital mucosa, secondary to a variety of pathogens. There is typically minimal cutaneous involvement in RIME. This contrasts with erythema multiforme (EM) in which characteristic targetoid lesions predominate, usually in isolation (EM minor), but in a subset of cases, with severe mucositis (EM major).

Wells Syndrome-Like Histologic Pattern Caused by a Permanent Tattoo.

Tattoo reactions have become more common as tattoos gain visibility and popularity worldwide. A variety of inflammatory patterns have been described in association with tattoos- more commonly fibrosing, granulomatous, lichenoid, pseudolymphomatous, and spongiotic patterns. To date, there has been one case report of a Wells syndrome-like inflammatory pattern associated with a temporary Henna tattoo.

An Immune Suppression-associated EBV-positive Anaplastic Large Cell Lymphoma With a BRAF V600E Mutation.

Iatrogenic lymphoproliferative disorders have been described in patients receiving immunosuppressive/immunomodulatory agents outside the transplantation setting. Novel biological agents such as TNF-α blockers and JAK-inhibitors have also proven to be effective in many disorders including rheumatoid arthritis, inflammatory bowel disease (ulcerative colitis and Crohn disease), psoriasis, and others. A significant dilemma exists in those lymphoproliferative disorders associated with immunosuppressants and rheumatologic conditions, that relies on whether the association of the process is with the medication or the underlying autoimmune condition.

Lymphocytes in Sweet syndrome: A potential diagnostic pitfall.

Background: Patients with Sweet syndrome (SS) have acute onset of cutaneous lesions with characteristic histopathology (dense and diffuse neutrophilic infiltrate, dermal edema, leukocytoclasis and no vasculitis) accompanied by systemic symptoms. Sometimes, only skin lesions with classic histopathologic features are seen. Although SS is considered to be a "neutrophilic dermatosis," lymphocytes are also seen on histological examination.

Primary cutaneous aggressive epidermotropic cytotoxic T-cell lymphomas: reappraisal of a provisional entity in the 2016 WHO classification of cutaneous lymphomas.

Primary cutaneous CD8-positive aggressive epidermotropic T-cell lymphoma is a rare and poorly characterized variant of cutaneous lymphoma still considered a provisional entity in the latest 2016 World Health Organization Classification of Cutaneous lymphomas. We sought to better characterize and provide diagnostic and therapeutic guidance of this rare cutaneous lymphoma. Thirty-four patients with a median age of 77 years (range 19-89 years) presented primarily with extensive annular necrotic plaques or tumor lesions with frequent mucous membrane involvement.

Linear Sclerodermoid Lupus Erythematosus Profundus in a Child.

Lupus erythematosus panniculitis, also known as lupus profundus, is a variant in the clinicopathological spectrum of lupus erythematosus (LE) affecting about 2%-3% of LE patients. A linear configuration of LE panniculitis has been reported rarely with rare reports describing the coexistence of different forms of cutaneous LE and localized morphea. In this study, the authors present a 9-year-old girl with linear arrangement of subcutaneous nodules on her left forearm.

Pseudo-Bullous Dermatosis Induced by Topical Anesthetic Agent-Clues to This Localized Toxic Reaction.

Eutectic mixture of 2.5% lidocaine and 2.5% prilocaine (EMLA AstraZeneca, DE) is a widely used topical anesthetic cream for preprocedural cutaneous analgesia.

Cystic acantholytic dyskeratosis of the vulva: An unusual presentation of a follicular adnexal neoplasm.

Acantholytic dyskeratosis (AD) is a histologic pattern seen in Darier's disease or dyskeratosis follicularis, warty dyskeratoma, and transient AD. This pattern is characterized by suprabasilar clefting, acantholysis, and formation of corps ronds and grains. We present a case of AD that is unique based on its genital location and cystic architecture.

Two cases of systemic mantle cell lymphoma involving the skin.

Mantle cell lymphoma (MCL) is a form of non-Hodgkin lymphoma that rarely affects skin. Cutaneous involvement is non-specific but usually indicates widespread disease. Herein we present two cases of MCL with secondary skin involvement.

Pseudoepitheliomatous Hyperplasia in a Red Pigment Tattoo: A Separate Entity or Hypertrophic Lichen Planus-like Reaction?

Red pigment tattoos are known to cause pseudoepitheliomatous hyperplasia in the skin, frequently simulating squamous cell carcinoma or keratoacanthoma. Herein, the authors present two additional cases of red pigment tattoo pseudoepitheliomatous hyperplasia in which they noted a lichenoid tissue reaction. They reviewed the previously published cases and observed a lichenoid reaction in the histopathological images similar to hypertrophic lichen planus.

Hyperkeratotic variant of porokeratosis in a patient with Hepatitis C virus infection and a concomitant immunosuppressed state.

Porokeratoses are acquired and hereditary disorders of keratinization that share a distinctive lesion characterized by raised keratotic borders corresponding histologically to an angled column of parakeratotic cells, called a cornoid lamella. Although a precise mechanistic explanation is lacking, ultraviolet radiation and immunosuppressed states are considered causally-associated with most cases of acquired porokeratosis. Hepatitis C virus (HCV) infection has been proposed as a link between the immunosuppressed states and development of acquired porokeratosis.

Histopathologic Distinguishing Features Between Lupus and Lichenoid Keratosis on the Face.

Background: The occurrence of lichenoid keratosis (LK) on the face is not well characterized, and the histopathologic distinction between LK and lupus erythematosus (LE) occurring on the face is often indeterminate. The authors aimed to describe differences between LE and LK occurring on the face by hematoxylin and eosin alone.

Methods: Cases of LK and LE were obtained using computer-driven queries.

A Dermatopathologist's Guide to Troubleshooting Immunohistochemistry--Part 2: Troubleshooting Immunohistochemical Tests in the Laboratory.

Unexpected staining patterns can arise from problems occurring in any of the steps required for IHC, some of which are discussed in part I of this CME series. Whether used to differentiate benign from malignant tumors, identify tumor subtypes, subtypes of hematopoietic malignancies, or identifying targets for therapy, the pathologist must be intimately familiar with the potential pitfalls that are inherent in the IHC methodology to troubleshoot problems in the laboratory, and more importantly, when interpreting immunohistochemical staining, to avoid pitfalls of false-positive or false-negative stains.

A Dermatopathologist's Guide to Troubleshooting Immunohistochemistry Part 1: Methods and Pitfalls.

Immunohistochemistry (IHC) is a method by which specific target antigens can be detected in formalin-fixed paraffin-embedded tissue and involves the use of monoclonal or polyclonal antibodies; visualization of specific tissue antigens is achieved through an enzymatic reaction that transforms a colorless chromogen to a colored one. These enzymes may be attached to the antibody through a protein-ligand method (eg, biotin-avidin or biotin-streptavidin) or through a secondary antibody. Epitopes that are masked by protein linkage during formalin fixation are unmasked using a retrieval system that either uses heat (heat-induced epitope retrieval) or proteolytic enzymes (proteolytic-induced epitope retrieval).

Pseudocarcinomatous hyperplasia in anaplastic large cell lymphoma, a mimicker of poorly differentiated squamous cell carcinoma: report of a case and review of the literature.

Pseudocarcinomatous hyperplasia can occasionally be observed in biopsies of CD30-positive lymphoproliferative disorders. It is important to be cognizant of this association, because epithelial hyperproliferation can overshadow large atypical lymphoid cells, leading to an erroneous diagnosis of squamous cell carcinoma (SCC) or keratoacanthoma. Herein, we present a case of anaplastic large cell lymphoma (ALCL) with pseudocarcinomatous hyperplasia simulating a poorly differentiated carcinoma and review the literature on this subject.

Reduced Expression of RECK Protein May Help Differentiate Cutaneous Malignant Melanoma from Melanocytic Nevus.

Background: Differentiating between vertical growth cutaneous malignant melanoma (CMM) and predominantly intradermal benign melanocytic nevus (BMN) can be extremely challenging. Reversion-inducing cysteine-rich protein with Kazal motifs (RECK) is an endogenous inhibitor of many proteins that promote tumor invasion and progression. We investigated the difference in expression of RECK between CMM and BMN to determine whether RECK could assist in their differentiation.