Toxic Epidermal Necrolysis and Graft-versus-Host Reaction: Revisiting a Puzzling Similarity

Cytotoxic dermatitis: Review of the interface dermatitis pattern in veterinary skin diseases

Interface dermatitis or lichenoid interface dermatitis refers to a cutaneous inflammatory pattern in which keratinocyte cell death is the essential feature. These terms have evolved from the originally described lichenoid tissue reaction. These lesions are the basis for an important group of skin diseases in animals and people where cytotoxic T-cell-mediated epidermal damage is a major pathomechanism. Yet, for largely historical reasons these commonly used morphological diagnostic terms do not reflect the essential nature of the lesion. An emphasis on subsidiary lesions, such as the presence of a lichenoid band, and definitions based on anatomical features, such as location at the dermo-epidermal location, may cause confusion and even misdiagnosis. This review covers historical aspects of the terminology, including the origin of terms such as "lichenoid." The types of cell death involved and the histopathologic lesions are described. Etiopathogenesis is discussed in terms of aberrations of immune/inflammatory mechanisms focusing on cutaneous lupus erythematosus, erythema multiforme, and Stevens-Johnson syndrome/toxic epidermal necrolysis. Mechanisms have most extensively been studied in humans and laboratory animals and the discussion is centered on these species. As interface dermatitis is firmly entrenched in dermatological parlance, rather than using "cytotoxic" as its substitute, the terminologies "interface cytotoxic dermatitis" and "panepidermal cytotoxic dermatitis" are recommended, based on location and extent of epithelium affected.

Acute graft-versus-host disease presenting as Stevens-Johnson syndrome and toxic epidermal necrolysis: A retrospective cohort study

BACKGROUND

Cutaneous manifestations resembling Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) have been reported in patients with acute graft-versus-host disease (aGVHD); however, the clinicopathological characteristics of SJS/TEN-like aGVHD remain unexplored.

OBJECTIVE

To investigate the clinicopathology, complications, and outcomes of patients with SJS/TEN-like aGVHD.

METHODS

We analyzed a multicenter cohort of patients with aGVHD between 2000 and 2021.

RESULTS

We analyzed 31 patients with aGVHD, including SJS/TEN-like (n = 15) and non-SJS/TEN-like (n = 16). Patients with SJS/TEN-like aGVHD had significantly more extensive erythema and skin detachment/mucositis. SJS/TEN-like aGVHD was significantly associated with higher aGVHD grading and systemic complications, including pancytopenia, leukopenia, anemia, severe thrombocytopenia, coagulation abnormality, hepatitis, diarrhea, renal dysfunction, and bacteremia. A significantly lower hemoglobin/red cell distribution width ratio was identified in SJS/TEN-like aGVHD. Histopathology showed significant severe dyskeratosis and interface change. Patients with SJS/TEN-like aGVHD had lower 2-month survival rates and 5.35-fold higher 5-year mortality rates than those with non-SJS/TEN-like aGVHD. Total mortality rates of patients with SJS/TEN-like aGVHD reached 80% during follow-up; sepsis predominated the causes of death.

LIMITATIONS

Retrospective, nonrandomized study with a small sample size.

CONCLUSION

SJS/TEN-like aGVHD is associated with multiple systemic complications and high mortality. Early recognition, differential diagnosis from drug-induced-SJS/TEN, and appropriate treatment are critical.

Case Report: Toxic epidermal necrolysis associated with sintilimab in a patient with relapsed thymic carcinoma

Immune checkpoint inhibitors (ICIs) such as anti-programmed death 1 (PD-1) receptor monoclonal antibody has been shown to be effective in patients with relapsed thymic carcinoma. However, immune-related adverse events (irAE) are increasingly recognized. There is a paucity of clinical data, especially in elderly patients. A patient in his late 80s with a history of thymic carcinoma was treated with sintilimab, an anti-PD1 antibody. After one week of administration, the patient developed diffuse rash. After two cycles of sintilimab, there was rapid progression of the rash with gradual development of blisters and skin detachment. Sintilimab was immediately discontinued, and skin biopsy was performed. The histopathological findings were consistent with the diagnosis of toxic epidermal necrolysis (TEN), which was considered as an irAE. Intravenous methylprednisolone was initially administered, followed by oral prednisone. The patient showed dramatic improvement within 72 hours of initiation of treatment. Unfortunately, the patient died of severe pneumonia three months later. We report a case of TEN, a rare toxicity induced by anti-PD-1 sintilimab in an elderly patient with thymic carcinoma. Since TEN is a life-threatening condition, early recognition and management of this complication is a key imperative.

Immunometabolic Therapeutic Targets of Graft-versus-Host Disease (GvHD)

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative option in the treatment of aggressive malignant and non-malignant blood disorders. However, the benefits of allo-HSCT can be compromised by graft-versus-host disease (GvHD), a prevalent and morbid complication of allo-HSCT. GvHD occurs when donor immune cells mount an alloreactive response against host antigens due to histocompatibility differences between the donor and host, which may result in extensive tissue injury. The reprogramming of cellular metabolism is a feature of GvHD that is associated with the differentiation of donor CD4+ cells into the pathogenic Th1 and Th17 subsets along with the dysfunction of the immune-suppressive protective T regulatory cells (Tregs). The activation of glycolysis and glutaminolysis with concomitant changes in fatty acid oxidation metabolism fuel the anabolic activities of the proliferative alloreactive microenvironment characteristic of GvHD. Thus, metabolic therapies such as glycolytic enzyme inhibitors and fatty acid metabolism modulators are a promising therapeutic strategy for GvHD. We comprehensively review the role of cellular metabolism in GvHD pathogenesis, identify candidate therapeutic targets, and describe potential strategies for augmenting immunometabolism to ameliorate GvHD.

Incidence, Histopathological Features and Differential Diagnosis of Cutaneous Graft Versus Host Disease in Allogeneic Bone Marrow Transplantation

Objectives:

Hematopoietic stem cell transplantation by allogeneic bone marrow transplantation is a method used in the treatment of various genetic, immunological disorders, hematologic and solid organ malignancies. Graft versus Host Disease is one of the major and fatal complications of allogeneic bone marrow transplantation. It is a systemic disease affecting five main areas: skin, gastrointestinal tract, liver, lung and hematopoietic system. Diagnosis of cutaneous Graft versus Host Disease is made by the correlation between clinical and histopathological findings of the patient. The present study aims to investigate the incidence of cutaneous graft versus Host Disease in allogeneic bone marrow transplantation patients in our center, to discuss the histopathological features and differential diagnosis of cutaneous graft versus Host Disease in the light of the literature.

Methods:

The pathology slides of allogeneic bone marrow transplantation patients who were diagnosed as graft versus Host Disease in our pathology department between January 2015 and January 2019 were re-evaluated. Epidermal and dermal histomorphological findings of the disease were classified; the patients’ clinical and demographic information was obtained from the files. The incidence of cutaneous Graft versusHost Disease was calculated.

Results:

In our center, between January 2015 and January 2019, 273 pediatric and 100 adult patients underwent allogeneic and 181 autologous bone marrow transplantation. Twenty-three patients who underwent allogeneic bone marrow transplantation had cutaneous Graft versus Host Disease whereas and 21 patients had gastrointestinal Graft versus Host Disease. The incidence of cutaneous and gastrointestinal Graft versus Host Disease was 16.1% whereas the incidence of cutaneous Graft versus Host Disease was 8.42%. The most common clinical differential diagnosis of cutaneous Graft versus Host Disease was drug reaction (74%). The most common epidermal histomorphologic finding in our cases was keratinocyte necrosis (87%). In our cases, the most common epidermal histomorphologic finding was keratinocyte necrosis (87%). This was followed by vacuolar degeneration in basal keratinocytes (63%), acanthosis and spongiosis (61%), respectively. The most common finding in the dermis was pigment incontinence (59%). Of the patients with Graft versus Host Disease, 56% had transplantation from unrelated donors, whereas 44% of them had transplantation from their relatives.

Conclusion:

Cutaneous Graft versus Host Disease is a common complication of allogeneic hematopoietic stem cell transplantation. It is associated with high mortality rates and has a significant negative impact on the patient’s quality of life. Dermatological early recognition of the disease; histopathological evaluation and verification with differential diagnosis plays a key role in preventing patient morbidity and mortality.

Macrophage regulation of graft-vs-host disease

Hematopoietic stem cell transplantation has become a curative choice of many hematopoietic malignancy, but graft-vs-host disease (GVHD) has limited the survival quality and overall survival of hematopoietic stem cell transplantation. Understanding of the immune cells’ reaction in pathophysiology of GVHD has improved, but a review on the role of macrophages in GVHD is still absent. Studies have observed that macrophage infiltration is associated with GVHD occurrence and development. In this review, we summarize and analyze the role of macrophages in GVHD based on pathophysiology of acute and chronic GVHD, focusing on the macrophage recruitment and infiltration, macrophage polarization, macrophage secretion, and especially interaction of macrophages with other immune cells. We could conclude that macrophage recruitment and infiltration contribute to both acute and chronic GVHD. Based on distinguishing pathology of acute and chronic GVHD, macrophages tend to show a higher M1/M2 ratio in acute GVHD and a lower M1/M2 ratio in chronic GVHD. However, the influence of dominant cytokines in GVHD is controversial and inconsistent with macrophage polarization. In addition, interaction of macrophages with alloreactive T cells plays an important role in acute GVHD. Meanwhile, the interaction among macrophages, B cells, fibroblasts, and CD4+ T cells participates in chronic GVHD development.

Atypical cutaneous targetoid lesions after bone marrow transplant

A 69-year-old man with esophageal EBV-positive diffuse large B cell lymphoma status post allogeneic bone marrow transplant (BMT) five months prior presented to his oncologist with three days of maculopapular rash that was initially diagnosed as grade 1 graft-versus-host disease and started on oral prednisone. However, due to worsening of the rash, the patient presented to dermatology clinic, where skin biopsy revealed a diagnosis of erythema multiforme (EM). The patient improved with the use of topical steroids. This case highlights the atypical morphology of post-BMT EM and the potential causes for this atypical appearance.

The rash that presents as target lesions

We have explored the rash that appears as target lesions, with the central and dominant diseases belonging to the Stevens-Johnson syndrome/toxic epidermal necrolysis group. After presenting the clinical patterns of an individual target lesion and classifying them into different types of lesions, the contribution has been organized with groups characterized by such specific findings according to the type of lesion: flat or raised, typical or atypical, presence or absence of fever, presence or absence of mucosal ulcerations, presence or absence of arthralgias, and/or internal organ involvement. Other specific features, such as histologic appearance, immunofluorescence findings, and laboratory changes, are considered. We provide clinicians with an algorithmic, systematic, and logical approach to diagnose the condition of the patients who present with targetoid lesions, and enable them to differentiate between those with serious systemic and life-threatening diseases from others with ordinary skin ailments.

Toxic epidermal necrolysis in a child 6 months post-hematopoietic stem cell transplantation

TEN is a rare and critical disease mostly caused by drugs. It is mediated by activated CD8+ T cells that cause keratinocyte apoptosis with the assistance of cytokines/chemokines. We herein report a pediatric case of TEN after allogeneic HSCT with precursor B-cell acute lymphoblastic leukemia (pre-B-ALL) in second complete remission. Although we did not evaluate the T-cell subpopulation in blood or skin lesion of the patient, an imbalanced immune reconstitution after HSCT might additively contribute to the development of TEN.

Protomyofibroblast Pathway in Early Thermal Burn Healing

Wound healing following partial thickness thermal burns is commonly hampered by the risk of hypertrophic scarring. Skin myofibroblast (MF) density is commonly increased in postburn healing. The transition between fibroblast-like cells and α-smooth muscle actin (SMA)+ MF possibly begins with CD14+ monocytes, evolving to CD14+ CD34+ fibrocytes, followed by β-SMA+ protomyofibroblast (PMF) maturation. Skin biopsies from 25 burn patients were collected about 1 and 4 weeks after injury. Immunohistochemistry was performed using monoclonal antibodies to α-SMA, β-SMA, factor XIIIa, lysozyme, Mac 387, CD14, CD117 and Ulex europaeus agglutinin-1 (UEA-1). The set of Mac 387+ and CD14+ monocytes was accompanied by both CD34+ fibrocytes and factor XIIIa+ dendrocytes. By contrast, β-SMA+ PMF were rare. Of note, α-SMA+ MF were more abundant at week 4 than at week 1 (p < 0.01). The UEA-1+ endothelial cells showed marked variations in their dermal distribution, irrespective of the densities in the other scrutinized cells. In conclusion, healing of partial thickness thermal burns involves a diversity of cell types including PMF. In the present samples, the PMF density remained low. © 2015 S. Karger AG, Basel.

Erythema multiforme, Stevens-Johnson syndrome and toxic epidermal necrolysis: a comparative review

BACKGROUND

Human erythema multiforme (EM) and Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) are separate conditions. There is no consensus on classification criteria for the eponymous diseases in animals.

RESULTS

Animal EM is very different from 90% of human EM, which is herpes virus associated (HAEM). Animals lack acrally distributed, typical raised targets. Unlike canine parvovirus 'EM', HAEM is not an active infection. Animal EM is often attributed to drugs, but this is rarely proved. Conversely, human and animal SJS/TEN are almost identical, life-threatening disorders of epidermal necrosis and detachment, typically triggered by drugs (occasionally by infectious agents). Both EM and SJS/TEN are mediated by cytotoxic lymphocyte responses against altered keratinocytes (infectious agents or drugs). Apoptosis results from direct cytotoxicity or through soluble mediators, namely Fas ligand, granzymes, perforin and granulysin. Diagnosis in humans is clinicopathological, with emphasis on clinical lesions; histopathology confirms the pathological process as interface (cytotoxic) dermatitis. Human EM is self-limiting; only recurrent and rare persistent cases require antiviral/immunosuppressive therapies. Drug-induced EM responds to drug withdrawal. Idiopathic canine EM (>40%) is usually chronic, refractory to treatment and may represent heterogeneous conditions. Early identification and removal of the causative drug and high-quality supportive care are critical in SJS/TEN. Mortality rate is nevertheless high.

CONCLUSIONS AND CLINICAL IMPORTANCE

(1) Histopathological lesions do not reliably differentiate EM, SJS and TEN. (2) A multicentre study to develop a consensus set of clinical criteria for EM and SJS/TEN in animals is overdue. (3) No adjunctive therapies, including intravenous immunoglobulin and ciclosporin, have met evidence-based standards.