Myelodysplasia cutis and VEXAS syndrome initially diagnosed as histiocytoid Sweet syndrome: A diagnostic pitfall.

Histiocytoid Sweet syndrome (H-SS) is a histopathological variant of Sweet syndrome (SS) defined by cutaneous infiltration of immature myeloid cells morphologically resembling histiocytes. The association of H-SS with underlying malignancy, particularly myelodysplastic syndromes, is well-established. Myelodysplasia cutis (MDS-cutis) has been proposed to describe cases historically diagnosed as H-SS but characterized by shared clonality of the myeloid infiltrate in skin and bone marrow. Therefore, identifying patients who might have MDS-cutis is critical for the management of the associated hematologic malignancy. VEXAS syndrome, an adult-onset autoinflammatory disease, should also be included in the histopathologic differential diagnosis of H-SS, as it shares clinical and pathologic features with MDS-cutis. Through the presentation of two cases, we aim to highlight the defining features and key clinical implications of MDS-cutis and VEXAS syndrome.

Neonatal Sweet syndrome with associated rectovestibular fistula and review of the literature.

An otherwise healthy 4-week-old term female of Japanese heritage presented with a 1-week history of asymptomatic progressive, generalized skin lesions. The lesion morphology, distribution, and dermatopathology result was consistent with Sweet syndrome. The patient was found to have a congenital type H rectovestibular fistula. This case highlights the rare association of rectovestibular fistula in neonatal Sweet syndrome which has only been described in neonates of Japanese heritage.

Sweet syndrome in pregnancy: A narrative review.

The aim of this review is to increase obstetrician awareness of pregnancy-associated Sweet syndrome. Patients present with fever, leukocytosis, and skin eruption, which can mimic other infectious or inflammatory conditions, but do not respond to antibiotics. A search using PubMed, EMBASE, and Web of Science Core Collection was conducted to review all reported cases of pregnancy-associated Sweet syndrome, an acute febrile neutrophilic dermatosis occurring during pregnancy or postpartum. A total of 33 episodes among 30 patients were identified, with the majority (54.5% [18]) of cases occurring within the second trimester. Among the 30 patients, skin lesions most commonly affected the head and neck (73.3% [22]), with rare oral or ocular involvement. Leukocytosis was the most common laboratory finding, reported in 96.7% [29] of patients, with neutrophil predominance noted in 70.0% [21]. The diagnosis was confirmed for all patients with pathognomonic results of skin biopsies. Of the 27 cases detailing treatment, systemic corticosteroids were most frequently used (19 cases), followed by conservative management (seven cases), and dapsone (one case). The dapsone-treated patient and 15 of the 19 steroid-treated patients experienced resolution, but additional management strategies were required in the remaining four individuals. Spontaneous resolution occurred during pregnancy in six of the seven conservatively managed individuals, with one patient experiencing spontaneous abortion shortly after skin eruption at 10 weeks of gestation. No associated maternal deaths were reported. Obstetric complications of pregnancy-associated Sweet syndrome included endomyometritis, sterile placental abscesses, and abdominal wall necrosis. Delivery of healthy infants occurred in 24 of the 25 cases that presented fetal outcome, which included two infants who underwent medically indicated preterm deliveries.

A Rare Case of Drug-Induced Sweet Syndrome After Pembrolizumab Therapy.

Sweet syndrome is an uncommon inflammatory disorder characterized by the abrupt appearance of painful, erythematous papules, plaques, or nodules on the skin. Fever and leukocytosis frequently accompany the cutaneous lesions. In addition, involvement of the eyes, musculoskeletal system, and internal organs may occur. Sweet syndrome has been associated with a broad range of disorders. There are three subtypes: classical Sweet syndrome, malignancy-associated Sweet syndrome, and drug-induced Sweet syndrome. Classical Sweet syndrome is not associated with malignancy or drugs. It is essentially associated with an upper respiratory infection, gastrointestinal infection, inflammatory bowel disease, and pregnancy. Malignancy-associated Sweet syndrome is associated with hematologic malignancy more than solid malignancy, most commonly with acute myeloid leukemia. Drug-induced Sweet syndrome usually develops approximately two weeks after drug exposure, in patients who lack a prior history of exposure to the inciting drug. Here we are discussing our patient, a 68-year-old male who presented eight weeks after starting chemotherapy with pemetrexed, carboplatin, and pembrolizumab for left lung adenocarcinoma with macular rash. On further investigation with biopsy was found to have neutrophilic dermatitis, hence being diagnosed with drug-induced Sweet syndrome. Histopathology revealed a dermis with infiltration of neutrophils with lekocytoclasia.

VEXAS syndrome: A 2-case series report.

VEXAS syndrome is a rare entity secondary to UBA1 gene mutations, located on the X chromosome. This mutation generates, as a consequence, a characteristic vacuolation on haematopoietic stem-cells. It is characterized by multiple autoinflammatory and haematologic manifestations, which respond and end up being dependent on corticosteroid treatment. In this publication we present a 2-case series diagnosed at our hospital and make a brief literature review of the published evidence so far.

Suspected coexistence of perianal necrotizing sweet syndrome in chronic myelomonocytic leukemia: A case report.

BACKGROUND: Chronic myelomonocytic leukemia (CMML) complicated with Sweet syndrome (SS) is a rare hematological neoplasm. However, cases of concomitant development of perianal necrotizing SS (NSS) have not been reported. CASE SUMMARY: We report a case of a 49-year-old male patient who underwent sequential procedures for hemorrhoids and perianal abscess. He developed postoperative incision infection and was referred to the department where the authors work. Initially, perianal necrotizing fasciitis secondary to incision infection after perianal abscess surgery was suspected. Despite receiving antibiotic therapy and undergoing surgical debridement, deeper necrotic areas formed in the patient's perianal wounds, accompanied by persistent high fever. Blood and fungal cultures yielded negative results. The final diagnosis was corrected to be CMML with suspected concomitant perianal NSS. CONCLUSION: CMML with perianal NSS is a rare condition, often misdiagnosed as perianal abscess or perianal necrotizing fasciitis. Conventional antibiotic therapy and surgical debridement are ineffective in managing this condition.

Histiocytoid Sweet's Syndrome in the Setting of Myelodysplastic Syndrome.

Acute febrile neutrophilic dermatosis, or Sweet's syndrome, is characterized by tender, edematous papules and plaques, favoring the upper extremities and the head and neck regions. The classic variant of Sweet's syndrome involves a predominantly neutrophilic dermal infiltrate on histopathology. However, histiocytoid Sweet's syndrome has been noted to have a primary histiocytoid mononuclear infiltrate and is typically found in patients with malignancies such as myelodysplasia. This case report discusses the treatment of histiocytoid Sweet's syndrome in an immunocompromised patient with a recent history of Mycobacterium avium complex infection and latent tuberculosis in the setting of myelodysplastic syndrome.

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.

Sweet syndrome induced by FLT3 inhibitors: case report and literature review.

BACKGROUND: Acute febrile neutrophilic dermatosis, also commonly referred to as Sweet syndrome, is often associated with tumors, infections, immune disorders and medications. FLT3 inhibitor-induced Sweet syndrome is a rare complication. METHODS AND RESULTS: We report a patient with relapsed and refractory acute monocytic leukemia harboring high-frequency FLT3-ITD and DNMT3a mutations. The FLT3 inhibitor gilteritinib was administered for reinduction therapy after failure of chemotherapy with a combination of venetoclax, decitabine, aclarubicin, cytarabine and granulocyte colony-stimulating factor. The leukemia patient achieved remission after 1 month of treatment. However, Sweet syndrome induced by gilteritinib, which was confirmed by skin biopsy, developed during induction therapy. Similar cases of Sweet syndrome following FLT3 inhibitor therapy for acute myeloid leukemia were reviewed. CONCLUSION: Attention should be given to this rare complication when FLT3 inhibitors are used for acute myeloid leukemia therapy, and appropriate treatments need to be administered in a timely manner.

Proteasome inhibitor-associated histiocytoid Sweet's syndrome: Clinical and histological similarities to Nakajo-Nishimura syndrome suggest a potential mechanism.

Histiocytoid Sweet's syndrome (HSS) is a variant of Sweet's syndrome (SS) that clinically resembles SS but differs histologically by infiltrates, predominantly composed of immature cells of the myeloid lineage. Medications such as proteasome inhibitors have been reported to cause HSS but there has been little discussion on the underlying mechanism. Here we report two cases of HSS associated with a proteasome inhibitor. Both patients were on ixazomib for the treatment of multiple myeloma and presented with acute erythematous plaques on the upper half of the body. Pathological findings were consistent with HSS. Similarities between proteasome inhibitor-induced HSS and Nakajo-Nishimura syndrome, an inherited inflammatory disease, can be identified both clinically and histologically, suggesting a potential explanation of the mechanism behind proteasome inhibitor-associated HSS.

Periorbital necrotizing sweet syndrome: A report of two cases mimicking necrotizing soft tissue infections.

Purpose: Two cases are described of necrotizing Sweet syndrome (nSS), a rare variant of acute febrile neutrophilic dermatosis that mimics necrotizing soft tissue infections. Observation: A 74-year-old female with myelodysplastic syndrome (MDS) presented with isolated periorbital nSS that closely mimicked necrotizing fasciitis (NF); she displayed pathergy to debridement, was exquisitely responsive to corticosteroids, and underwent successful first-stage reconstruction of the eyelid with full-thickness skin grafting. A second 40-year-old female patient with relapsed acute myelogenous leukemia (AML) presented with multifocal nSS most prominently involving the eyelid. Positive herpes zoster virus (HSV) PCR and bacterial superinfection complicated the diagnosis. She improved with chemotherapy for AML and corticosteroid therapy. Conclusion: nSS is rare and a high level of clinical suspicion as well as an understanding of its distinguishing features is necessary to avoid undue morbidity. Identification of pathergy, histopathology, microbiology, and clinical context are critical to avoid misdiagnosis of infection.

Comparative immunohistochemical analysis of inflammatory cytokines in distinct subtypes of Sweet syndrome.

Background: A dysregulated immune response has been implicated in Sweet syndrome (SS) pathogenesis; however, cytokine profiles across different conditions associated with SS - including adult-onset immunodeficiency (AOID) due to anti-interferon (IFN)-γ autoantibodies - remain unknown. Objective: To investigate alterations in inflammatory cytokines in skin lesions of distinct subtypes of SS. Methods: Skin biopsies were collected from 42 AOID- and 52 non-AOID-associated SS patients and 18 healthy controls. The comparative immunohistochemical study was conducted using monoclonal antibodies against interleukin (IL)-1ß, IL-6, IL-17, IFN-γ, and tumor necrosis factor-α on paraffin-embedded sections. The quantitative percentage positivity and intensity were calculated using computer-based image analysis. Results: The results showed stronger and more diffuse dermal immunoreactivity for IFN-γ and IL-17 in the AOID-associated (p < 0.001 and p < 0.001, respectively) and non-AOID-associated SS (p < 0.001 and p < 0.001, respectively) groups. However, no significant differences in the levels of these two cytokines were observed between the AOID- and non-AOID-associated SS groups. Increased expression of IFN-γ together with IL-17 was also noted in almost all subtypes among non-AOID-associated SS. Conclusions: These results demonstrate that IFN-γ and IL-17 are implicated in immunopathology of all SS subtypes, including AOID-associated SS, despite the presence of anti-IFN-γ autoantibodies.

Pulmonary coccidioidomycosis mimicking malignancy associated with Sweet's syndrome (acute febrile neutrophilic dermatosis).

A suspicious malignant lung nodule with cutaneous reaction is not always cancer, especially in low risk for malignancy patients. A lung biopsy should be taken into consideration. The associated cause of Sweet's syndrome directs the treatment in each patient.