Acute inflammatory edema: A mimicker of cellulitis in critically ill patients

Cellulitis: A Review of Current Practice Guidelines and Differentiation from Pseudocellulitis

Cellulitis, an infection involving the deep dermis and subcutaneous tissue, is the most common reason for skin-related hospitalization and is seen by clinicians across various disciplines in the inpatient, outpatient, and emergency room settings, but it can present as a diagnostic and therapeutic challenge. Cellulitis is a clinical diagnosis based on the history of present illness and physical examination and lacks a gold standard for diagnosis. Clinical presentation with acute onset of redness, warmth, swelling, and tenderness and pain is typical. However, cellulitis can be difficult to diagnose due to a number of infectious and non-infectious clinical mimickers such as venous stasis dermatitis, contact dermatitis, eczema, lymphedema, and erythema migrans. Microbiological diagnosis is often unobtainable due to poor sensitivity of culture specimens. The majority of non-purulent, uncomplicated cases of cellulitis are caused by β-hemolytic streptococci or methicillin-sensitive Staphylococcus aureus, and appropriate targeted coverage of this pathogen with oral antibiotics such as penicillin, amoxicillin, and cephalexin is sufficient. Even with rising rates of community-acquired methicillin-resistant Staphylococcus aureus, coverage for non-purulent cellulitis is generally not recommended.

Superficial Angiomyxomas Frequently Demonstrate Loss of Protein Kinase A Regulatory Subunit 1 Alpha Expression: Immunohistochemical Analysis of 29 Cases and Cutaneous Myxoid Neoplasms With Histopathologic Overlap

Superficial angiomyxomas (SAMs) are benign cutaneous tumors that arise de novo and in the setting of the Carney complex (CC), an autosomal dominant disease with several cutaneous manifestations including lentigines and pigmented epithelioid melanocytomas. Although most SAM do not pose a diagnostic challenge, a subset can demonstrate histopathologic overlap with other myxoid tumors that arise in the skin and subcutis. Traditional immunohistochemical markers are of limited utility when discriminating SAM from histopathologic mimics. Since protein kinase A regulatory subunit 1 alpha (PRKAR1A) genetic alterations underlie most CC cases, we investigated whether SAM demonstrate loss of PRKAR1A protein expression by immunohistochemistry. In our series, 29 SAM, 26 myxofibrosarcoma, 5 myxoid dermatofibrosarcoma protuberans, 11 superficial acral fibromyxomas, and 18 digital mucous cysts were characterized. Of the 29 SAM examined in this study, 1 was associated with documented CC in a 5-year-old girl. SAM tended to arise in adults (mean 49.7 y; range: 5 to 87 y). Loss of PRKAR1A was seen in 55.2% of cases (16/29) and had a male predilection (87.5%, 12/16). PRKAR1A-inactivated SAM demonstrated significant nuclear enlargement (100%, 16/16 vs. 23.1%, 3/13), multinucleation (81.3%, 13/16 vs. 23.1%, 3/13), and presence of neutrophils (43.8%, 7/16 vs. 0%, 0/13). In contrast, PRKAR1A was retained in all cases of myxofibrosarcoma (100%, 26/26), myxoid dermatofibrosarcoma protuberans (100%, 5/5), superficial acral fibromyxomas (100%, 11/11), and digital mucous cyst (100%, 18/18). Taken together, PRKAR1A loss by immunohistochemistry can be used as an adjunctive assay to support the diagnosis of SAM given the high specificity of this staining pattern compared with histopathologic mimics.

Acute inflammatory edema as a variant of pseudocellulitis resolved after transcatheter aortic valve implantation

Acute inflammatory edema is a noninfectious inflammatory condition of the skin that is commonly seen in critically ill patients. It is characterized by edematous, erythematous, and nontender plaques involving the abdomen and thighs, sparing areas of the skin subject to pressure. Risk factors include fluid overload, hypoalbuminemia, and obesity. Differentiating acute inflammatory edema from cellulitis can be challenging. Supportive care is the mainstay therapy for acute inflammatory edema, with interventions primarily focused on lowering the fluid burden. We report an unusual case of a nonobese patient in the outpatient setting with acute inflammatory edema.

Acute Inflammatory Edema: A Case Report with Histopathological and Immunohistochemical Findings

Acute inflammatory edema (AIE) is a rare variant of pseudocellulitis characterized by blanchable, erythematous, and edematous plaques mainly on the thighs and abdomen and sparing areas of increased pressure. The condition occurs predominantly in critically ill patients with hypoalbuminemia, those with increased body mass index, and those with evidence of fluid overload. AIE was introduced in 2019; however, its histopathological picture has never been elucidated in the literature. We report a case of AIE in a 64-year-old Thai woman with several comorbidities and illustrate its histopathological and immunohistochemical features for the first time. Treatment with diuretics, fluid restriction, and adjuvant hemodialysis revealed marked improvement after ten days. Our report emphasizes that AIE is a distinct dermatosis with specific characteristics that help differentiate AIE from cellulitis and other pseudocellulitic conditions. Furthermore, our observations support the role of lymphatic alterations in the pathogenesis of the disease.

Skin Eruptions in Acute Hemorrhagic Edema of Young Children: Systematic Review of the Literature

BACKGROUND

Acute hemorrhagic edema is a skin-limited small-vessel leukocytoclastic vasculitis, which affects infants 4 weeks to 2 years of age and remits within 3 weeks. The diagnosis is made clinically in not-ill appearing children with acute onset of raised annular or nummular eruptions and edema. In this vasculitis, type, distribution, and evolution of the rash have never been systemically investigated. To address this issue, we employed the data contained in the Acute Hemorrhagic Edema Bibliographic Database, which incorporates all reports on acute hemorrhagic edema.

SUMMARY

Key features of rash were documented in 383 children. Annular eruptions in a strict sense, usually targetoid, were reported in 375 (98%) cases (many children also presented polycyclic or arciform eruptions). Nummular eruptions were also very common (n = 358; 93%). Purpuric eruptions and ecchymoses were reported in the vast majority of cases. Macules and wheals were described in a minority of cases. Edema, detected in all cases, was mostly painful, indurated and nonpitting. The following regions were affected, in decreasing order, by annular or nummular eruptions: legs, feet, face, arms, ears, trunk, and genitals. With the exception of feet, which were very often affected, the same distribution was reported for edema. The initial eruption was often a wheal or a macule that evolved into a nummular or an annular eruption. Nummular eruptions successively evolved into annular ones.

KEY MESSAGE

This study carefully characterizes type, distribution, and evolution of skin eruption in acute hemorrhagic edema. The data help physicians to rapidly and noninvasively make the clinical diagnosis of this vasculitis.

Clinical and immunologic differences in cellulitis vs. pseudocellulitis

Introduction: The immunologic mechanisms between cellulitis and pseudocellulitis differ greatly, even though their clinical presentations may overlap.Areas covered: This article discusses cellulitis and common entities within the pseudocellulitis spectrum including acute lymphedema, superficial venous thrombosis, allergic contact dermatitis, lipodermatosclerosis, stasis dermatitis, erythema nodosum, cutaneous gout, and bursitis. The literature search was conducted from PubMed search engine between March and May 2021.Expert commentary: While immunologic differences in cellulitis and the various entities of pseudocellulitis are clear, there is a practice gap in applying these differences to the clinic and hospital setting. Further, existing studies are weakened by the lack of a gold-standard diagnosis in this disease category. Additional work is necessary in developing a gold-standard for the diagnosis and secondly, to project these immunologic differences as biomarkers to differentiate sterile inflammation from a potential life threatening bacterial or fungal infection.