Hepatic acetyl CoA links adipose tissue inflammation to hepatic insulin resistance and type 2 diabetes.

Impaired insulin-mediated suppression of hepatic glucose production (HGP) plays a major role in the pathogenesis of type 2 diabetes (T2D), yet the molecular mechanism by which this occurs remains unknown. Using a novel in vivo metabolomics approach, we show that the major mechanism by which insulin suppresses HGP is through reductions in hepatic acetyl CoA by suppression of lipolysis in white adipose tissue (WAT) leading to reductions in pyruvate carboxylase flux. This mechanism was confirmed in mice and rats with genetic ablation of insulin signaling and mice lacking adipose triglyceride lipase. Insulin's ability to suppress hepatic acetyl CoA, PC activity, and lipolysis was lost in high-fat-fed rats, a phenomenon reversible by IL-6 neutralization and inducible by IL-6 infusion. Taken together, these data identify WAT-derived hepatic acetyl CoA as the main regulator of HGP by insulin and link it to inflammation-induced hepatic insulin resistance associated with obesity and T2D.

Cytophagic histiocytic panniculitis leading to a diagnosis of acute myeloid leukemia with monocytic differentiation: A case report and literature review.

Cytophagic histiocytic panniculitis (CHP) is associated with a number of systemic conditions and is characterized by the presence of benign phagocytic histiocytes ("bean bag cells"), including phagocytosed erythrocytes, leukocytes, and platelets. We describe a case of a 72-year-old female who presented with a papular eruption that clinically mimicked pityriasis lichenoides et varioliformis acuta (PLEVA). Given that her skin biopsy had multiple features concerning PLEVA, this diagnosis was classified as a superficial pityriasis lichenoides-like variant of CHP. The histopathologic presence of cytophagic histiocytosis prompted workup for a systemic malignancy, leading to a diagnosis of underlying acute monocytic leukemia of myeloid lineage.

Ruxolitinib Monotherapy for a Child With HAVCR2 Gene Mutation Associated Subcutaneous Panniculitis-like T-cell Lymphoma: A Case Report.

BACKGROUND: The occurrence of hemophagocytic lymphohistiocytosis (HLH) in patients with subcutaneous panniculitis-like T-cell lymphoma (SPTCL) may be due to HAVCR2 gene mutation, leading to T-cell immunoglobulin and mucin domain-containing molecule 3 deficiency, T-cell and macrophage activation, and proinflammatory cytokine production. OBSERVATION: We report a patient with SPTCL and HLH for whom ruxolitinib, used as a novel treatment, showed notable therapeutic effects. CONCLUSIONS: Remission of both HAVCR2 mutation-induced high inflammatory characteristics and significant symptoms post-ruxolitinib administration suggested that patients with SPTCL and HLH may not represent typical lymphoma cases. Ruxolitinib, with its relatively low toxic side effects, can provide favorable outcomes.

Atypical and Typical Presentation of Erythema Nodosum: Clinical Differences in Treatment and Outcome.

INTRODUCTION: Erythema nodosum (EN) is the most common form of panniculitis that predominantly affects the shins. While EN in atypical sites has been described by many authors, there are currently only case studies published on this topic. This study aimed to evaluate clinical differences between patients suffering from EN on the shins, compared to patients with EN in atypical locations. METHODS: We analyzed 105 patients in a retrospective, single-center study at a university hospital in Switzerland. Typical EN was defined as lesions, found only on the lower legs, while atypical EN as lesions on the upper legs, trunk, arms, or face, only or in addition to lesions on the lower legs. The patients were assessed for age, gender, dermatologic history, time until first medical consultation, time to diagnosis, and time until remission. Further, etiology, symptoms, and applied therapies were investigated. Findings were then compared between the typical and atypical EN cohorts. RESULTS: Overall, we included 70 patients (37.99 ± 15.67 [3-81] years) with EN solely on the shins and 35 patients (41.27 ± 16.85 [9-76] years) with EN on other locations. Interestingly, time until diagnosis was significantly shorter in atypical EN (p = 0.034, 1.14 ± 4.68 vs. 0.46 ± 1.14 months). Time to remission was similar in both groups (3.61 ± 2.73 vs. 3.05 ± 2.86 months, respectively). Sarcoidosis was the only etiologic factor significantly more frequent in atypical EN compared to typical EN (23% vs. 9%, p = 0.042). Besides that, solely subtle differences were seen regarding etiology, gender, age at onset, course of the disease, and symptoms. CONCLUSIONS: Our study suggests that only minor alterations between both study populations exist. Significant differences were found in time to diagnosis (shorter for atypical EN), as well as in sarcoidosis as an etiologic factor (more frequent in atypical EN). While adalimumab was only prescribed in atypical EN cases, prognosis seems to be similar for typical and atypical EN (similar time to remission, similar amount of reoccurring cases). Due to the limited sample size, however, our study population may have been too small to detect the relevant differences, and bigger studies may be needed.

Granulomatous Panniculitis as an Initial Manifestation of Sjögren Syndrome.

ABSTRACT: A 65-year-old woman presented with unexplained weight loss, recurrent fever, and a dermatosis with painful nodules on the extremities. Biopsies showed focal lobular panniculitis with neutrophilic microgranulomas. Comprehensive investigations ruled out infection and hematologic and solid organ neoplasms. Laboratory results showed anti-Ro/SSA and anti-La/SSB antibody positivity, and elevated inflammatory markers. Dry mouth and eye were confirmed. The diagnosis of Sjögren syndrome with cutaneous panniculitis was established. Prednisone treatment with 30 mg/d resulted in remission of fever and pain improvement. This case emphasizes Sjögren syndrome as an autoimmune disease with multiple cutaneous manifestations and highlights its association with granulomatous panniculitis.

Subcutaneous panniculitis-like T-cell lymphoma: Morphological, immunophenotypical and clonality assessment in six cats.

BACKGROUND: Primary cutaneous lymphoma represents 0.2%-3% of all feline lymphomas, with nonepitheliotropic lymphomas being the most common. In humans and dogs, subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a primary nonepitheliotropic lymphoma with a T-cell phenotype developing in the subcutis and often mimicking inflammation. OBJECTIVE: The aim of this report is to describe pathological, phenotypical and clonal features of SPTCL in cats. ANIMALS: Six cats with SPTCL were included in this study. MATERIALS AND METHODS: Skin biopsies were formalin-fixed, routinely processed and stained. Histological and immunohistochemical investigation for anti-CD18, CD204, CD79a, CD20, CD3, FeLVp27and FeLVgp70 and clonality assessment were performed. RESULTS: Four male and two female domestic shorthair cats, mean age 11.2 years, developed SPTCL in the abdominal (three), inguinal (two) and thoracic (one) regions. Variably pleomorphic neoplastic lymphoid cells were present in the panniculus in percentages, expanding the septa (six of six) and extending into fat lobules in one of six cats. Tumours were associated with elevated numbers of neutrophils (five of six), lesser macrophages (six of six) and variable necrosis (six of six). Neoplastic cells expressed CD3+ (six of six), with clonal T-cell receptor rearrangement detected in five of six cats. CONCLUSIONS AND CLINICAL RELEVANCE: This is the first description of SPTCL in cats. Lesions can be confused with panniculitis, leading to delay in diagnosis and therapy. Awareness of this neoplastic disease is relevant to avoid misdiagnoses and to gain greater knowledge about the disease in cats.

Immune-mediated pyogranulomatous panniculitis with hypercalcemia in a dog.

An 11-year-old neutered male large crossbreed dog was presented for investigation because of a 10-day history of progressive lethargy, hyporexia, and pyrexia. Physical and dermatological examinations were unremarkable. Blood biochemical analysis identified a marked total and ionized hypercalcemia and increased C-reactive protein concentration. Bicavitary computed tomography screening for causes of the dog's clinical and biochemical abnormalities identified a diffuse panniculitis. Histopathological examination of full-thickness skin biopsies was consistent with pyogranulomatous inflammation. Extensive histochemical staining revealed no infectious etiology. Complete clinical and biochemical remissions were observed after starting immunosuppressive, followed by tapering, doses of prednisolone, supporting an immune-mediated etiology. Key clinical message: Sterile, immune-mediated pyogranulomatous inflammation should remain a differential diagnosis for hypercalcemia in dogs. Significant dermatological disease may occur without visible abnormalities.

Panniculite pyogranulomateuse à médiation immunitaire avec hypercalcémie chez un chienUn grand chien croisé mâle castré de 11 ans a été présenté pour examen en raison d'antécédents de léthargie progressive, d'hyporexie et de pyrexie depuis 10 jours. Les examens physiques et dermatologiques étaient sans particularité. L'analyse biochimique du sang présentait une hypercalcémie totale et ionisée marquée et une concentration accrue de protéine C-réactive. Le dépistage par tomodensitométrie bicavitaire des causes des anomalies cliniques et biochimiques du chien a identifié une panniculite diffuse. L'examen histopathologique des biopsies cutanées de pleine épaisseur était compatible avec une inflammation pyogranulomateuse. Un examen par coloration histochimique extensive n'a révélé aucune étiologie infectieuse. Les rémissions cliniques et biochimiques complètes ont été observées après le début du traitement immunosuppresseur, suivies d'une diminution progressive des doses de prednisolone, confirmant une étiologie à médiation immunitaire.Message clinique clé:L'inflammation pyogranulomateuse stérile à médiation immunitaire doit rester un diagnostic différentiel de l'hypercalcémie chez le chien. Une maladie dermatologique importante peut survenir sans anomalies visibles.(Traduit par Dr Serge Messier).

Subcutaneous panniculitis-like T-cell lymphoma in two unrelated individuals with BENTA disease.

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare primary cutaneous non-Hodgkin lymphoma involving CD8+ T cells, the genetic underpinnings of which remain incompletely understood. Here we report two unrelated patients with B cell Expansion with NF-κB and T cell Anergy (BENTA) disease and a novel presentation of SPTCL. Patient 1 presented early in life with recurrent infections and B cell lymphocytosis, linked to a novel gain-of-function (GOF) CARD11 mutation (p.Lys238del). He developed SPTCL-like lesions and membranoproliferative glomerulonephritis by age 2, treated successfully with cyclosporine. Patient 2 presented at 13 months with splenomegaly, lymphadenopathy, and SPTCL with evidence of hemophagocytic lymphohistiocytosis. Genetic analysis revealed two in cis germline GOF CARD11 variants (p.Glu121Asp/p.Gly126Ser). Autologous bone marrow transplant resulted in SPTCL remission despite persistent B cell lymphocytosis. These cases illuminate an unusual pathological manifestation for BENTA disease, suggesting that CARD11 GOF mutations can manifest in cutaneous CD4+and CD8+ T cell malignancies.

Efficacy of ruxolitinib for HAVCR2 mutation-associated hemophagocytic lymphohistiocytosis and panniculitis manifestations in children.

Frequent germline mutations of HAVCR2, recently identified in subcutaneous panniculitis-like T-cell lymphoma (SPTCL), are associated with an increased risk of hemophagocytic lymphohistiocytosis (HLH). However, SPTCL-HLH represents a challenge because of the difficulties in treatment with poor survival. Its malignant nature, specifically harbouring HAVCR2 mutations, has also been questioned. To better understand its pathology and treatment, we analysed the clinical data of six patients diagnosed at our centre. The median age at onset was 10.5 years (range, 0.8-12.4). Five patients presented with skin lesions of subcutaneous nodules/plaques and/or ulceration. All patients developed HLH; notably, one infant only had HLH without skin involvement. Histopathologically, only two patients were diagnosed with SPTCL and three were reported as panniculitis with no sufficient evidence of lymphoma. Genetically, germline homozygous mutation of HAVCR2 (p.Y82C) was identified in all patients, with a median diagnosis time of 4.6 months. All patients initially received corticosteroids, immunosuppressants or chemotherapy, achieving unfavourable responses. Strikingly, they responded well to ruxolitinib targeting inflammatory cytokines, allowing rapid disease resolution and/or long-term maintenance of remission. The excellent efficacy of ruxolitinib highlights this disease as an inflammatory condition instead of neoplastic nature and indicates novel agents targeting key inflammatory pathways as an encouraging approach for this disease entity.

Germline HAVCR2 mutations and their relation to the clinical spectrum of subcutaneous panniculitis-like T-cell lymphoma and hemophagocytic lymphohistiocytosis: results from a multicenter study and meta-analysis.

Germline HAVCR2 mutations are frequently detected in subcutaneous panniculitis-like T-cell lymphoma (SPTCL) patients with/without hemophagocytic lymphohistiocytosis (HLH) but factors associated with variable manifestations remain undetermined. To evaluate clinical variations and associated factors in SPTCL and/or HLH with/without HAVCR2 mutations, we performed direct sequencing of HAVCR2 exon 2 using DNA from patients with SPTCL or idiopathic HLH/HLH-like systemic illnesses, defined by HLH alone without secondary causes. The systematic review and individual patient data (IPD) level meta-analysis which included the present and previously published studies reporting HAVCR2 mutations in SPTCL with/without HLH populations was subsequently conducted using random-effects meta-analysis and multivariate logistic regression. Among 34 patients enrolled, ten of 28 SPTCL patients developed HLH/HLH-like systemic illnesses. Six cases with HAVCR2Y82C mutation manifested with HLH without panniculitis. Male sex (P=0.03) and age <18 years (P=0.04) were associated with HLH, corresponding to the inverse correlation between age and HLH-2004 score (r=-0.40; P=0.02). Homozygous HAVCR2Y82C mutation was more common in the presence of HLH compared with the absence (75.0% vs. 44.4%; P=0.02). Using IPD from the present and the other three eligible cohorts (N=127), male sex, heterozygous and homozygous/compound heterozygous HAVCR2 mutations were associated with HLH by the adjusted odds ratio of 2.93 (95% confidence interval [CI]: 1.22-7.06), 4.77 (95% CI: 1.05-21.63) and 8.48 (95% CI: 2.98-24.10), respectively. Patients with male sex and/or germline HAVCR2 mutations showed an increased risk of developing HLH. Younger patients tended to manifest with HLH, while older patients typically presented with SPTCL with less frequent HLH/HLH-like systemic illnesses.

Erythema nodosum in children: a cohort study from a tertiary pediatric hospital in Italy.

Erythema nodosum (EN), although relatively uncommon in the pediatric population, is the most frequent type of panniculitis in children. The present study aimed to report all the cases of children admitted to our tertiary pediatric hospital with the diagnosis of EN to evaluate the epidemiology, clinical manifestations, etiology, treatment, and the course of this disease in the pediatric age. This observational study retrospectively considered all children evaluated to the emergency room (ER) of Meyer Children's University Hospital, Florence, Italy, discharged with a diagnosis of EN over a 12-year period (from January 2009 to December 2021). Clinical and laboratory data were recorded using a standardized report form. Sixty-eight patients with EN were included. The etiologic diagnosis of EN was made in 38 children (55.9%): 29 (42.6%) had infection-related EN (in particular EBV and ß-hemolytic streptococcus), 6 (8.8%) had Crohn's disease, 1 celiac disease, 1 Sjogren syndrome, and 1 Hodgkin lymphoma. In 30 patients (45%), no definitive diagnosis was reached, and they were defined as having idiopathic EN. Most of the laboratory tests were nonspecific. No statistical differences were found in the demographic and clinical data, and the main diagnostic laboratory parameters between patients with idiopathic EN versus those with secondary EN.  Conclusion: Since EN can be isolated or the first manifestation of heterogeneous underlying pathologies, some of which can be severe and life-threatening, it is important to recognize it and carry out all the necessary etiological diagnostic investigations to understand its etiology and start the specific treatment. What is Known: • Erythema nodosum (EN) is the most frequent type of panniculitis in children. • It has been associated with a wide spectrum of disorders, such as different types of infection, malignancies, chronic inflammations, and drugs. What is New: • No statistical differences can be found in clinical features as well as laboratory data, between patients with idiopathic EN versus those with secondary EN. • A broad spectrum of investigations and a proper follow-up should be taken into account in order to prevent a delayed or missed secondary EN diagnosis.

Common superficial and deep cutaneous bacterial infections in domestic animals: A review.

The skin covers the external surface of animals, and it is constantly exposed to and inhabited by different microorganisms, including bacteria. Alterations in the skin barrier allow commensal and/or pathogenic bacteria to proliferate and penetrate deep into the lower layers of the skin. Being the first barrier to the external environment, the skin is prone to injuries, allowing the penetration of microorganisms that may lead to severe deep infections. Companion animals, especially dogs, are prone to bacterial infections, often secondary to allergic dermatitis. When environmental conditions are unfavorable, horses, cattle, sheep, and goats can develop superficial infections, such as those caused by Dermatophilus congolensis. Deep inflammation is commonly caused by Mycobacterium spp., which results in granulomatous to pyogranulomatous dermatitis and panniculitis. Likewise, bacteria such as Nocardia spp. and Actinomyces spp. can cause deep pyogranulomatous inflammation. Bacteria that lead to deep necrotizing lesions (eg, necrotizing fasciitis/flesh-eating bacteria) can be severe and even result in death. This review includes an overview of the most common cutaneous bacterial infections of domestic animals, highlighting the main features and histologic morphology of the bacteria, cutaneous structures involved, and the type of inflammatory infiltrates.

Superficial (nodular) thrombophlebitis as a heterogeneous entity with distinctive clinico-pathological aspects: Correlation with the underlying conditions.

BACKGROUND: Superficial (nodular) thrombophlebitis, referring to a thrombo-inflammatory disorder of dermal-subcutaneous veins, encompass a spectrum of nodular lesions often associated with inflammatory, infectious, neoplastic or thrombophilic diseases. OBJECTIVE: We postulate that distinct clinico-pathological features may correlate with the underlying conditions. METHODS: We conducted a retrospective monocentric study of all patients seen in our dermatology department for a superficial thrombophlebitis, completed with a literature review. Clinical and pathological data were extracted from the patient files and articles. RESULTS: A total of 108 cases of superficial thrombophlebitis was analysed. Forty-five percent manifested as elongated nodules clearly evoking vascular involvement, while the other 55% were presenting as nodules or plaques. The elongated phenotype was strongly associated with malignancy or thrombophilia if a pure thrombosis was demonstrated histopathologically, while tuberculosis was the main underlying condition if a granulomatous vasculitis was present. Panniculitis-like lesions were mainly corresponding to erythema-nodosum-like lesions of Behçet's disease, characterized by the distinctive feature of thrombotic veins with an associated leukocytoclastic vasculitis. LIMITATIONS: Retrospective design and risk of publication bias. CONCLUSION: Superficial (nodular) thrombophlebitis is a heterogeneous entity with a distinct clinico-pathological presentation that strongly points to the nature of the underlying medical condition, thus guiding the medical workup.

Self-induced panniculitis in adolescence: Three cases and review of the literature.

Self-induced trauma is a rare cause of panniculitis in adolescents and may be associated with undiagnosed underlying psychological conditions. The condition often poses a diagnostic challenge as patients usually present with non-specific signs and symptoms, and often a concealed history of self-induced trauma. Here, we present three adolescent patients with self-induced traumatic panniculitis. All three patients were repeatedly admitted with non-specific cutaneous lesions as well as multiple somatic complaints. After extensive evaluation to exclude organic causes, psychiatric assessment eventually revealed underlying psychosomatic disorders as a cause of the self-induced trauma.

Rapid cytologic diagnosis of subcutaneous fat necrosis of the newborn.

Subcutaneous fat necrosis of the newborn is a rare self-limited panniculitis that classically presents within the first few weeks of life. The diagnosis is typically clinical, but some cases require skin biopsy with hematoxylin and eosin stain for confirmation. We report a previously undocumented rapid diagnostic protocol that involves collecting a small amount of exudate from a suppurative lesion, placement onto a slide without fixation, and simply viewing the material under a microscope. This novel and practical method of diagnosis reveals doubly refractile crystals diagnostic of subcutaneous fat necrosis without a biopsy, which may be helpful for rapid diagnosis or use in low resource settings.

Erythema nodosum associated with COVID19 infection: A pediatric case report and review of the literature.

Erythema nodosum (EN) is a common panniculitis characterized by tender erythematous nodules predominantly on the pretibial area and represents a hypersensitivity reaction to multiple triggers. COVID19 infection and vaccination have been associated with EN in the adult population. We report a pediatric case of EN following COVID19 infection and review the literature on COVID19 infection and COVID19 immunization-related EN.

Progressive nodule-like lesions on bilateral lower limbs.

Pancreatic panniculitis is a rare disease characterized by subcutaneous fat necrosis. It could be the result of an associated pancreatic tumor. Herein, we reported a 63-year-old man who presented with progressive bilateral lower limb edema accompanied with nodule-like lesions for 1 month. His serum lipase was 3,927 U/L (normal, 0-160 U/L). Histopathology of the skin specimen revealed lobular panniculitis, favoring a diagnosis of pancreatic panniculitis. Abdominal computed tomography (CT) scan with contrast showed a huge mass in his left upper quadrant. Endoscopic ultrasound showed a mixed echoic tumor, measuring 11.9 × 7.8 cm in dimensions, originating from the pancreatic tail. Biopsy performed via an endoscopic ultrasound showed a poorly differentiated acinar cell carcinoma. Because of the unresectable status of the tumor, the patient underwent chemotherapy with paclitaxel and gemcitabine. After chemotherapy, his skin lesions improved progressively. It is important to treat pancreatic panniculitis with its underlying pancreatic disease.

Early-onset recurrent panniculitis as a phenotype of NLRC4-associated autoinflammatory syndrome: Characterization of pathogenicity of the p.Ser445Pro NLRC4 variant.

Monoallelic NLRC4 gain-of-function variants cause an inflammasomopathy with diverse clinical forms including infantile enterocolitis, recurrent macrophage activation syndrome, cold-induced urticaria-like lesions (or familial-cold autoinflammatory syndrome, FCAS4), and painful subcutaneous nodules. Here, we identified a large family with six consecutive generations affected. Genetic analyses detected the heterozygous p.Ser445Pro NLRC4 variant in three patients, which has been previously reported in a Dutch family with FCAS4. We aimed to describe the clinicopathological features and the functional consequences of the detected NLRC4 variant. Patients presented an early-onset (3 months-6 years) inflammatory disease characterized by recurrent panniculitis, fever and arthralgia. Histopathological examination showed perivascular and interstitial lymphohistiocytic infiltrates in the dermis and mixed panniculitis. Functional analysis supported the conclusion that the p.Ser445Pro NLRC4 variant leads to a constitutive activation of NLRC4-inflammasome and increased plasma levels of IL-18. Prompt recognition of early-onset panniculitis through clinicopathological examination and laboratory biomarkers may allow targeted therapies.

Painful subcutaneous nodules in an alcoholic: a case of pancreatic panniculitis.

Pancreatic panniculitis is an uncommon manifestation of pancreatic disease, affecting approximately 2-3% of patients with acute or chronic pancreatitis [1]. Its accurate diagnosis is crucial for effective treatment as skin manifestations usually precede systemic symptoms of pancreatitis. The diagnosis of pancreatic panniculitis requires identifying and confirming pancreatic disease in addition to the typical histopathological findings of lobular panniculitis without vasculitis. Herein, we present a patient with pancreatic panniculitis, underlying acute pancreatic failure, and kidney injury.

Linear discoid lupus erythematous simulating en coup de sabre morphea in a female chronic granulomatous disease carrier.

Discoid lupus erythematosus (DLE), a subtype of chronic cutaneous lupus may be observed in a linear pattern. A 21-year-old woman with history of chronic granulomatous disease state presented to our clinic for a chronic six-year skin eruption on her left eyebrow, left cheek, and left forehead. A punch biopsy of involved left forehead skin was performed and revealed perivascular and periadnexal lymphohistiocytic infiltrate without features of morphea or panniculitis, confirming the histopathologic changes of cutaneous lupus erythematous. The patient was diagnosed with linear DLE, mimicking en coup de sabre, within Blaschko lines. The pathogenesis for DLE in association with chronic granulomatous disease is ambiguous; however, X-linked lyonization is crucial for both conditions and may explain cooccurrence of disease states.