Sweet's syndrome and erythema nodosum: two neutrophilic dermatoses?

Subcutaneous Sweet's Syndrome Presenting With a Single Cutaneous Lesion on the Thigh

Sweet's syndrome (SS), also known as acute febrile neutrophilic dermatosis, manifests as tender, erythematous skin lesions such as papules, nodules, and plaques that may appear vesicular or pustular. The condition is characterized by widespread infiltrates mainly consisting of mature neutrophils, usually in the upper dermis. Erythema nodosum (EN) is a form of septal panniculitis marked by tender, erythematous lesions primarily appearing on the lower legs. Additionally, subcutaneous Sweet's syndrome (SSS) is a rare variant of SS that mainly involves the subcutaneous adipose tissue. Skin lesions in SSS generally present as tender, erythematous subepidermal nodules on the extremities, morphologically resembling EN. Both EN and SS can present with fever, malaise, gastrointestinal disturbances, lymphadenopathy, arthralgia, increased white blood cell (WBC) count with neutrophilia, elevated C-reactive protein (CRP), and elevated erythrocyte sedimentation rate (ESR), making differentiation between them often challenging. Therefore, histopathologic evaluation is necessary for an accurate diagnosis. In our case, the patient exhibited a very painful plaque measuring 20 cm in diameter on the upper thigh without significant neutrophil infiltration in the dermis, but with subcutaneous septal neutrophil infiltration. Generally, SS shows stronger leukocytosis with neutrophilia than EN does. Considering the clinical symptoms, laboratory results, and clinical progression, the clinicopathological findings aligned more closely with SSS than EN. This article describes a rare case of SSS presenting with a single cutaneous lesion on the thigh, which mimicked the histopathological features of EN.

Sweet or Not? Azathioprine-Induced Sweet Syndrome Mimicking Erythema Nodosum in a Patient With Inflammatory Bowel Disease

This case report highlights the clinical challenge and need to distinguish Sweet syndrome and erythema nodosum (EN) in a 50-year-old woman with newly initiated azathioprine for inflammatory bowel disease. While she initially presented with clinical features concerning for drug-induced Sweet syndrome, a subsequent histopathological examination confirmed early-stage EN. Both Sweet syndrome and EN share common triggers and therapeutic responses, but have distinctive clinical characteristics. Subtle histologic differences also exist in lesion distribution and depth of infiltration. This case underscores the need for accurate differentiation in patients with inflammatory bowel disease to initiate appropriate management and avoid potential complications.

Elevated neutrophil to lymphocyte ratio as an indicator of secondary erythema nodosum, a retrospective observational study

Background/aim

Erythema nodosum (EN) is an inflammatory disorder of subcutaneous tissue. Although etiopathogenesis of the disease is unknown, many predisposing factors such as infections, systemic disease, and drugs have been identified. Neutrophil to lymphocyte ratio (NLR) has been shown to be a novel inflammatory marker in many dermatological diseases. The aim of our study is to investigate NLR in EN patients and evaluate its relation to the underlying cause of the disease.

Materials and methods

Between 2014 and 2018, clinical and laboratory data of 395 patients diagnosed with EN and 395 controls were extracted from patient files. EN patients were grouped as idiopathic EN and secondary EN (EN with an identified underlying cause). Clinical and laboratory characteristics of the two groups were compared

Results

NLR was elevated in EN patients compared to controls (median of 2.38 vs. 1.55, P < 0.001). Among EN patients, NLR was also elevated in patients with secondary EN. In multivariate logistic regression model NLR (> 2.11), RDW-CV (> 13.65), and CRP (> 5.5) were identified as risk factors for secondary EN (relative risks were 17.16, 2.69, and 2, respectively).

Conclusion

Elevated NLR (> 2.11) may be used as a parameter to discriminate secondary EN from idiopathic EN.

Erythema nodosum in an adolescent patient with cryopyrin-associated periodic syndrome

Cryopyrin-associated periodic syndrome (CAPS) is a monogenetic auto-inflammatory disorder with systemic manifestations. Innate immune system aberrance is seen in both CAPS and erythema nodosum and this case may point to a previously unknown association. In pediatric patients with EN and systemic features, the possibility of underlying CAPS should be considered.

Clinical, histopathological, and immunological evaluation of a series of patients with erythema nodosum

BACKGROUND

The pathogenesis of erythema nodosum (EN) is still poorly understood, and studies evaluating the involvement of a cytokine network are very scarce.

OBJECTIVES

To investigate clinical and pathological features, the cytokine profiles, and the balance of T-regulatory (Treg) and T-helper (Th)17 cells in serum and lesional skin of patients with EN.

METHODS

Patients with a diagnosis of EN were consecutively enrolled, and their clinical and histopathological features were recorded. A panel of cytokines was evaluated in both serum and lesional skin using enzyme-linked immunosorbent assay. Real-time polymerase chain reaction was performed to evaluate the Treg/Th17 cell balance.

RESULTS

Histopathological examination of skin biopsy specimens from all patients (four women and one man) showed classical features of EN. The most widely expressed cytokines were innate immunity cytokines (mainly tumor necrosis factor alpha, interleukin-8 and -6) and growth factors (mainly granulocyte colony-stimulating factor and monocyte chemoattractant protein-1). The Treg/Th17 balance was highly different between patients.

CONCLUSIONS

The present study emphasizes the crucial role of neutrophils in the pathogenesis of EN, as high levels of cytokines and growth factors mainly involved in neutrophil recruitment and activation were detected.

Concurrence of Sweet's syndrome, pathergy phenomenon and erythema nodosum-like lesions

We report the case of a 54-year-old woman with concurrent Sweet's syndrome, pathergy phenomenon and eythema nodosum-like lesions associated with suppurative tonsillitis. Tender, violaceous and highly edematous papules and plaques were detected on the forearms and legs, some of which were pseudovesicular. Similar edematous papules were detected on the dorsum of the hands at the sites of intravenous injection. Biopsies of a plaque on the forearm and a papule at the site of intravenous injection confirmed the presence of Sweet's syndrome. Multiple, tender, violet-red, subcutaneous erythematous nodules were revealed on the legs. A biopsy taken from a nodule on the leg revealed septal panniculitis. To our knowledge, no patient with concurrent Sweet's syndrome, pathergy phenomenon, and erythema nodosum-lesions had been reported yet in previous literature.

Sweet's syndrome--a comprehensive review of an acute febrile neutrophilic dermatosis

Sweet's syndrome (the eponym for acute febrile neutrophilic dermatosis) is characterized by a constellation of clinical symptoms, physical features, and pathologic findings which include fever, neutrophilia, tender erythematous skin lesions (papules, nodules, and plaques), and a diffuse infiltrate consisting predominantly of mature neutrophils that are typically located in the upper dermis. Several hundreds cases of Sweet's syndrome have been published. Sweet's syndrome presents in three clinical settings: classical (or idiopathic), malignancy-associated, and drug-induced. Classical Sweet's syndrome (CSS) usually presents in women between the age of 30 to 50 years, it is often preceded by an upper respiratory tract infection and may be associated with inflammatory bowel disease and pregnancy. Approximately one-third of patients with CSS experience recurrence of the dermatosis. The malignancy-associated Sweet's syndrome (MASS) can occur as a paraneoplastic syndrome in patients with an established cancer or individuals whose Sweet's syndrome-related hematologic dyscrasia or solid tumor was previously undiscovered; MASS is most commonly related to acute myelogenous leukemia. The dermatosis can precede, follow, or appear concurrent with the diagnosis of the patient's cancer. Hence, MASS can be the cutaneous harbinger of either an undiagnosed visceral malignancy in a previously cancer-free individual or an unsuspected cancer recurrence in an oncology patient. Drug-induced Sweet's syndrome (DISS) most commonly occurs in patients who have been treated with granulocyte-colony stimulating factor, however, other medications may also be associated with DISS. The pathogenesis of Sweet's syndrome may be multifactorial and still remains to be definitively established. Clinical and laboratory evidence suggests that cytokines have an etiologic role. Systemic corticosteroids are the therapeutic gold standard for Sweet's syndrome. After initiation of treatment with systemic corticosteroids, there is a prompt response consisting of dramatic improvement of both the dermatosis-related symptoms and skin lesions. Topical application of high potency corticosteroids or intralesional corticosteroids may be efficacious for treating localized lesions. Other first-line oral systemic agents are potassium iodide and colchicine. Second-line oral systemic agents include indomethacin, clofazimine, cyclosporine, and dapsone. The symptoms and lesions of Sweet's syndrome may resolved spontaneously, without any therapeutic intervention; however, recurrence may follow either spontaneous remission or therapy-induced clinical resolution.