The Mayo Clinic Histiocytosis Working Group Consensus Statement for the Diagnosis and Evaluation of Adult Patients With Histiocytic Neoplasms: Erdheim-Chester Disease, Langerhans Cell Histiocytosis, and Rosai-Dorfman Disease

Advances in Understanding and Management of Erdheim-Chester Disease

Erdheim Chester Disease (ECD) is a rare histiocytic disorder marked by infiltration of organs with CD68+ histiocytes. ECD stems from mutations of BRAF and MAP2K1 in hematopoietic stem and progenitor cells (HSPCs), which further differentiate into monocytes and histiocytes. Histopathology reveals lipid-containing histiocytes, which test positive for CD68 and CD133 in immunohistochemistry. Signs and symptoms vary and depend on the organ/s of manifestation. Definitive radiological results associated with ECD include hairy kidney, coated aorta, and cardiac pseudotumor. Treatment options primarily include anti-cytokine therapy and inhibitors of BRAF and MEK signaling.

Erdheim-Chester disease with tendon and muscle involvement: Reports of a rare presentation

Erdheim-Chester disease (ECD) is a rare histiocytic disease that affects multiple systems in the body. While it typically targets long bones, cardiovascular structures, the retroperitoneum, and the central nervous system, reports of tendon and skeletal muscle involvement are scarce. This review presents 2 cases: a case of ECD involving the left Achilles tendon and left abductor hallucis, as well as an unusual manifestation of ECD in the thigh musculature. In Case 1, studies involved a 39-year-old man who initially presented with bone and pituitary involvement. An order for 18F-FDG PET/CT imaging was placed by marked swelling in the patient's left ankle and observed soft tissue fullness on foot radiographs, which revealed a soft tissue mass involving the left Achilles tendon, which arose along the tendon-muscle junction and involved the left abductor hallucis muscle. In Case 2, studies involved a 41-year-old man who initially presented with involvement of the cardiovascular system and retroperitoneum. 18F-FDG PET/CT scan showed an infiltrative right atrial mass and hypermetabolic lesion in the left external obturator muscle, extending to the left pectineus and right quadratus femoris muscle. Involvement of the Achilles tendon and skeletal muscle involvement, including left abductor hallucis muscle and medial thigh muscles, is one of the rare manifestations of ECD. Diagnostic delays were frequent due to the condition's rarity and nonspecific multisystemic symptoms. This should be considered in patients who present with myositis, tendinopathy, and bone pain and have other unexplained multisystemic problems.

Erdheim-Chester disease as complex clinical presentation and diagnosis: A case report and concise review of literature

RATIONALE

Erdheim-Chester disease (ECD) is a rare multisystemic disease characterized by the infiltration of multiple organs by foamy CD68 + CD1a-histiocytes. The genetic background consists of gain-of-function somatic mutations in the mitogen-activated protein kinase pathway. The purpose of the present paper is to make a contribution to the scientific literature on ECD by reporting our experience with a complex clinical case report, along with a concise review of the literature. We discussed the unusual clinical presentation, the complex diagnostic process and the comparison with other published cases.

PATIENT CONCERNS

A 70-year-old man presented with arthralgia due to multiple bone areas of sclerosis, first diagnosed with metastases of a prostatic neoplasm. Sequential thorax-abdomen, femoral and homer contrast-enhanced computed tomography (CT) showed pericardial effusion, pulmonary fibrosis, and perirenal fibrous tissue as "hairy kidneys." He underwent. Three bone biopsies were unsuccessful to reach diagnosis.

DIAGNOSES

A xanthelasma biopsy showed histopathological signs compatible with ECD; genetic analysis showed the mutation BRAFV600E.

INTERVENTIONS

The patient underwent targeted therapy with vemurafenib (BRAF-inhibitor), discontinued 2 weeks later due to the onset of a diffuse erythematous papular rash on the trunk and limbs.

OUTCOMES

At the 1-year follow-up, there was only progression of chronic kidney disease (CKD).

LESSONS

The present case report describes how ECD diagnosis could represent a challenge for clinicians, owing to its heterogeneous clinical presentation. Early diagnosis followed by prompt therapy is essential for modifying the natural history of the disease.

A rare presentation of Rosai-Dorfman disease as a single dural-based lumbar intradural lesion: A case report

Central nervous system Rosai Dorfman disease (RDD) is a rare condition and it is just reported in 5% of 600 registered RDD cases. In previously reported patients, the intradural extramedullary spinal lesion is extremely rare. In this article, we aim to report a case of intradural extramedullary Rosai-Dorfman lesion of the lumbar spine which was managed with gross total resection. Lumbar meningioma was the pre-operative diagnosis for this patient, the final correct diagnosis of Rosai-Dorfman disease was made after histological examination. RDD should be considered in the differential diagnosis of single intradural extramedullary lesions of the lumbar spine.

Isolated Rosai-Dorfman disease of the spine: A systematic literature review

INTRODUCTION

Rosai-Dorfman disease (RDD) is a rare non-Langerhans cell histiocytosis involving the central nervous system in 5% of cases. Spinal location occurs in less than 1% of extranodal RDD and can be responsible for neurological manifestations. We present a systematic review of cases of isolated spinal RDD. We also report a new case of isolated spinal RDD revealed by spinal cord compression.

MATERIALS AND METHODS

The systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline using the MEDLINE and SCOPUS databases and included case reports and case series describing isolated RDD of the spine.

RESULTS

There were 53 patients with isolated spinal RDD (including our case). The mean age was 35.85±16.48 years. Neurological deficit was the most frequent clinical presentation (89%). RDD lesions were mainly located in the thoracic spine (51%), then the cervical spine (32%). The lesion was reported to be extradural (57%), intradural extramedullary (26%), intramedullary (7%), and in the vertebral body (10%). Histological examination showed emperipolesis in 73%. Histocytes were positive for S-100 protein in 83%. Treatment was based on surgery 96%), radiotherapy, chemotherapy, and adjunctive steroid therapy were indicated in four, one, and eight cases. After a mean follow-up period of 14.84±13.00 months, recurrence of RDD was noted in 15%.

CONCLUSION

Spinal RDD is a rare condition, requiring meticulous histological examination for accurate diagnosis. Complete surgical resection is the treatment of choice. Adjuvant chemotherapy and radiotherapy can also be indicated in patients demonstrating partial improvement following surgery.

Extranodal Rosai-Dorfman Disease: a rare presentation involving anterior chest wall in a middle-aged female

Rosai-Dorfman Disease is a rare benign disorder involving overproduction of immune cells, causing swollen lymph nodes and, in rare cases, the sternum. The sternal involvement may cause chest pain and masses. Diagnosis is confirmed through clinical examination, biopsy, and imaging. Treatment options may include surgery, radiation, or steroids. In this case study, we present an unusual example of extranodal Rosai-Dorfman Disease involving the sternum, bilateral clavicles and first three ribs, and pectoral muscle with no associated lymphadenopathy or systemic symptoms in a 57-year-old female. The etiology, pathology, immunohistochemistry, imaging findings, and treatment options of this unique disease are discussed.

Imaging features of ALK-positive histiocytosis with neurological involvement: a case report and literature review

Background

ALK-positive histiocytosis is an exceptionally rare neoplasm of histiocytes that predominantly involves the nervous system and can also affect the skin and other parts of the body. Previous relevant literature has provided limited information regarding the imaging manifestations of this disease with neurological involvement.

Methods

We reported a case of ALK-positive histiocytosis with multisystem involvement. Together with a comprehensive literature review, the imaging characteristics of this disease in the nervous system were summarized.

Results

A 3-year-old girl with abdominal pain and ambulation difficulty checked in at the Department of Pediatric Neurology. The initial diagnosis was "acute cerebellitis with ataxia" based on the elevated protein level in the cerebrospinal fluid (CSF). However, despite 3 months of treatment, her condition deteriorated. MRI showed an oval-shaped, intradural extramedullary nodule at the T6-T7 level. The patient was ultimately diagnosed as ALK-positive histiocytosis, accompanied by cauda equina and skin involvement. The literature review showed a total of 23 patients who had involvement of the nervous system and provided imaging descriptions. Together with our case, the imaging features were summarized as follows: iso-dense or slightly hyperdense on computed tomography (CT), isointense or iso-hypointense on T2-weighted imaging (T2WI), moderate homogeneous enhancement with mildly/markedly punctate enhancement or/and smooth ring enhancement on contrast-enhanced T1-weighted imaging (T1WI), restricted diffusion on diffuse weighted imaging (DWI), and elevated fluorodeoxyglucose (FDG) uptake on positron-emission tomography/computed tomography (PET/CT).

Conclusion

The multimodal imaging findings of ALK-positive histiocytosis exhibit distinct characteristics, familiarity with which will enhance radiologists' expertise and facilitate accurate diagnosis of this disease.

Dabrafenib and steroids for the treatment of Erdheim-Chester disease with extensive CNS involvement: a case report

Erdheim-Chester disease (ECD) is an exceedingly rare non-Langerhans cell CD68+ CD1a- S100- histiocytic multi-organ disease. Diagnosis of ECD is often delayed due to non-specific radiographic findings and heterogeneous lesional tissue. Increasingly, the role of genomic alterations is being recognized for both diagnosis and treatment of ECD. More than half of ECD patients harbor the BRAFV600E mutation. Evaluation for this mutation be can falsely negative on immunohistochemical staining and confirmation with molecular analyses is recommended. We present a case of the 44 year-old male with BRAFV600E-positive ECD treated successfully with steroids followed by single-agent dabrafenib.

The role of 2-[18F]FDG PET/CT in Erdheim-Chester disease

OBJECTIVE

To analyze the body distribution of Erdheim-Chester disease (ECD) and determine the utility of 2-[18 F]FDG PET/CT compared to other imaging techniques. Additionally, to assess the aggressiveness and extent of the disease based on the presence/absence of the BRAFV600E mutation.

MATERIALS AND METHODS

The 2-[18F]FDG-PET/CT scans of all patients diagnosed with ECD between 2008 and 2021 were reviewed, including 19 patients. The affected territories were classified as detectable by PET/CT or detectable only by other imaging techniques (bone scintigraphy, contrast-enhanced CT, or MRI). Descriptive analysis and correlation of the BRAF mutation with the affected organs and maximum SUV were performed using the Student's t-test.

RESULTS

Out of the 19 patients (14 males; mean age 60.3 years), 11 had the BRAFV600E mutation. A total of 127 territories (64 organ-systems) affected were identified using different imaging modalities, of which 112 were detected by PET/CT, and an additional 15 territories were solely identified by cerebral and cardiac MRI. The presence of BRAFV600E mutation was associated with greater organ involvement (p < 0.05) without differences in SUVmax (p > 0.05).

CONCLUSION

2-[18F]FDG PET/CT is a highly effective diagnostic tool in patients with ECD, detecting the majority of affected territories. MRI was the only imaging modality with additional findings in territories showing high physiological uptake of 2-[18F]FDG (cerebral and cardiac). The presence of the BRAFV600E mutation correlated with a higher extent of the disease.

Rheumatic masqueraders: mimics of primary vasculitis - a case-based review

INTRODUCTION

Vasculitis conditions are often serious and sometimes fatal diseases, therefore it is paramount to diagnose correctly and treat appropriately. Mimics of primary vasculitis can include either non-inflammatory syndromes or secondary vasculitis where the underlying etiology of the vasculitis is being driven by infection, malignancy, drug-effect or other.

AREAS COVERED

This review comprises six individual cases of vasculitis mimics. Each case is presented and the clinical, radiographic, and histological features that distinguish the case from primary vasculitis are highlighted. Key mimics in large, medium and small vessel vasculitis are outlined.

EXPERT OPINION

The diagnosis of vasculitis requires a comprehensive assessment of clinical, radiographic, and histologic features. Clinicians should be familiar with mimics of primary vasculitis conditions. In the case of non-inflammatory mimics, it is important to differentiate from primary vasculitides in order to avoid unnecessary and potentially harmful immunosuppression. For cases of secondary vasculitis, identification of the correct etiologic cause is critical because treatment of the underlying stimulus is necessary for successful management and outcomes.

Double Subclavian Steal Syndrome As Initial Manifestation of Erdheim-Chester Disease: A Case Report

Erdheim-Chester disease (ECD) is a histiocytosis that infiltrates all organs, but especially large arteries such as the aorta and its branches, which become sheathed and lead to multiple stenoses or even occlusions. Subclavian steal syndrome (SSS) has not been reported in ECD. A 68-year-old female was diagnosed with ECD due to the typical sheathing of the aorta and its major branches. Five years previously, asymptomatic SSS due to stenosis of the left subclavian artery was incidentally diagnosed. In the following years, occlusion of the subclavian and left vertebral artery, and stenosis of basilar artery and right middle cerebral artery occurred. The abnormal cerebral perfusion had consequences on the perfusion of the left upper extremity and was presumably responsible for falls. Basilar and middle cerebral artery stenosis is rare in ECD and vertebral artery occlusion and double subclavian steal have not been reported in ECD. This case is the first to show that the initial manifestation of ECD can be unilateral SSS and that subclavian artery occlusion can even lead to double SSS. Patients with SSS should undergo a thorough diagnostic evaluation to detect rare causes of SSS, such as ECD.

BRAF testing modalities in histiocytic disorders: Comparative analysis and proposed testing algorithm

OBJECTIVES

Understanding of histiocytic disorders has been revolutionized by demonstration of mitogen-activated protein kinase (MAPK) pathway mutations, most commonly BRAFV600E. The optimal testing strategy to assess BRAFV600E is unknown. We aimed to compare performance of testing modalities, to propose a framework for evaluation of BRAFV600E mutation status in histiocytic disorders.

METHODS

We retrospectively reviewed patients with histiocytic disorders and BRAF mutation testing on a lesional tissue specimen.

RESULTS

In 120 patients, BRAF assessment included immunohistochemistry (IHC) in 97 (80.2%), polymerase chain reaction (PCR) in 35 (28.9%), and next-generation sequencing (NGS) in 62 (51.2%). Forty-five underwent both NGS and IHC. With NGS as the gold standard, the sensitivity and specificity of IHC were 82.4% and 96.4%. Three false negatives were observed in biopsy specimens with low BRAFV600E variant allele frequency or decalcified tissue. One false-positive IHC was observed in a lung biopsy specimen, likely due to antibody cross-reactivity with respiratory cilia. Among 14 with successful NGS and PCR, a single discordance was observed. Two PCR-to-IHC discrepancies were observed, including one other false-positive IHC.

CONCLUSIONS

Immunohistochemistry was highly specific for detection of BRAFV600E. Main caveats were false negatives and lack of detection of non-BRAFV600E mutations. We propose the use of IHC as initial screening in general practice with reflex molecular testing if negative.

Comparison of neuroimaging features of histiocytic neoplasms with central nervous system involvement: a retrospective study of 121 adult patients

OBJECTIVES

To compare neuroimaging characteristics of three types of histiocytoses, namely Langerhans cell histiocytosis (LCH), Erdheim-Chester disease (ECD), and Rosai-Dorfman disease (RDD), with central nervous system (CNS) involvement.

METHODS

A total of 121 adult patients with histiocytoses (77 LCH, 37 ECD, and 7 RDD) and CNS involvement were retrospectively included. Histiocytoses were diagnosed based on histopathological findings combined with suggestive clinical and imaging features. Brain and dedicated pituitary MRIs were systematically analyzed for tumorous, vascular, degenerative lesions, sinus, and orbital involvement and for hypothalamic pituitary axis involvement.

RESULTS

Endocrine disorders, including diabetes insipidus and central hypogonadism, were more common in LCH patients than in ECD and RDD patients (p < 0.001). In LCH, tumorous lesions were mostly solitary (85.7%), located in the hypothalamic pituitary region (92.9%), and without peritumoral edema (92.9%), while in ECD and RDD, tumorous lesions were often multiple (ECD: 81.3%, RDD: 85.7%), their distribution was more widespread with meninges mostly involved (ECD: 75%, RDD: 71.4%), and they most likely presented with peritumoral edema (ECD: 50%, RDD: 57.1%; all p ≤ 0.020). Vascular involvement was an exclusive imaging characteristic of ECD (17.2%), which was not observed in LCH or RDD; this was also associated with a higher risk of death (p = 0.013, hazard ratio = 11.09).

CONCLUSION

The typical characteristic of adult CNS-LCH was endocrine disorders with radiological findings limited to the hypothalamic pituitary axis. The pattern of multiple tumorous lesions with predominant involvement of meninges was the main manifestation of CNS-ECD and CNS-RDD, while vascular involvement was pathognomonic for ECD and associated with poor prognosis.

CLINICAL RELEVANCE STATEMENT

Involvement of the hypothalamic-pituitary axis is the typical imaging characteristic of Langerhans cell histiocytosis. Multiple tumorous lesions, predominantly involving but not limited to meninges, occur in most Erdheim-Chester disease and Rosai-Dorfman disease patients. Vascular involvement occurs only in Erdheim-Chester disease patients.

KEY POINTS

• The different distribution patterns of brain tumorous lesions can help differentiate among LCH, ECD, and RDD. • Vascular involvement was an exclusive imaging finding of ECD and was associated with high mortality. • Some cases with atypical imaging manifestations were reported to further expand the knowledge on these diseases.

Erdheim-Chester Disease Due to a Novel Internal Duplication of NRAS: Response to Targeted Therapy with Cobimetinib

Histiocytoses encompass a group of exceptionally rare disorders characterized by the abnormal infiltration of tissues by histocytes. Among these, Erdheim-Chester disease (ECD) stands out as a multisystem histiocytosis that typically affects bones and various other tissues. Historically, the treatment of ECD has been challenging. However, recent breakthroughs in our understanding, particularly the discovery of somatic mutations in the RAS-MAPK pathway, have opened new opportunities for targeted therapy in a significant subset of patients with ECD and other histiocytoses. In this report, we present the case of a patient with ECD harboring a previously unidentified microduplication in the NRAS gene in a small fraction of skin cells. This discovery played a pivotal role in tailoring an effective therapeutic approach involving kinase inhibitors downstream of NRAS. This case underscores the crucial role of deep sequencing of tissue samples in ECD, enabling the delivery of personalized targeted therapy to patients.

Differential Diagnosis of Tumor-like Brain Lesions

Purpose of Review

Tumor-like brain lesions are rare and commonly suggest a neoplastic etiology. Failure to rapidly identify non-neoplastic causes can lead to increased morbidity and mortality. In this review, we describe 10 patients who presented with atypical, non-neoplastic tumor-like brain lesions in which brain biopsy was essential for a correct diagnosis and treatment.

Recent Findings

There has been increasing recognition of autoimmune conditions affecting the nervous system, and many of those diseases can cause tumor-like brain lesions. Currently available reports of non-neoplastic tumor-like brain lesions are scarce. Most case series focus on tumefactive demyelinating lesions, and a comprehensive review including other neuroimmunological conditions such as CNS vasculitis, neurosarcoidosis, histiocytic and infectious etiologies is lacking.

Summary

We review the literature on tumor-like brain lesions intending to increase the awareness and differential diagnosis of non-neoplastic brain tumor mimics. We advocate for earlier brain biopsies, which, in our case series, significantly changed diagnosis, management, and outcomes.

[Histiocytosis]

Histiocytosis is a group of rare diseases characterized by inflammation and accumulation of cells derived from monocytes and macrophages in different tissues. The symptoms are highly variable, from mild forms with involvement of a single organ to severe multisystem forms that can be life compromising. The diagnosis of histiocytosis is based on the clinic, radiological findings and pathological anatomy. A biopsy of the affected tissue is recommended in all cases as it may have therapeutic implications. During the last decade, some mutations have been identified in the affected tissue that condition activation of the MAPK/ERK and PI3K/AKT pathway, in a variable proportion depending on the type of histiocytosis. In this review we mainly focus on Langerhans Cell Histiocytosis, Erdheim-Chester Disease and Rosai-Dorfman Disease.

Erdheim-Chester disease with bilateral orbital masses and multi-systemic symptoms: two case reports

BACKGROUND

Erdheim-Chester disease (ECD) is a rare histiocytic disorder characterized by multisystem xanthogranulomatous infiltration by lipid-laden histiocytes. We report two cases of ECD involving the orbit and describe their clinicopathologic factors, treatments, and prognosis. One was a rare case of ECD complicated with primary thrombocytosis.

CASE PRESENTATION

This study describes two patients with bilateral orbital ECD. Both presented with proptosis and visual loss; imaging findings showed bilateral intraorbital masses. Both had different degrees of systemic symptoms (pleural effusion, pericardial effusion, ascites, and heart failure) before the ocular symptoms and did not find the cause before ophthalmic tumor resection and pathological biopsy. The diagnosis of ECD was confirmed after pathological biopsy and detection of BRAF^V600E mutation. Patient 2 also with primary thrombocytosis and had a CALR mutation as well as the BRAF^V600E mutation. Both patients were recommended to receive targeted therapy. Patient 1 refused targeted therapy for financial reasons and was discharged after local radiotherapy only. The patient had no light perception in either eye and no improvement in systemic symptoms. Patient 2 began targeted treatment after diagnosis and reached the discharge criteria 2 weeks later. He is in good condition at present, but unfortunately, his eyesight has not improved because of the irreversible damage to his visual function.

CONCLUSION

ECD is easily misdiagnosed and missed because of its rarity and diverse clinical manifestations. Orbital involvement is common in ECD, and surgery is the most frequently employed approach. Despite the surgical resection is not curative, its significance lies in biopsy to establish diagnosis and/or surgical debulking to relieve mass effect, minimizing further impairment of visual function. Targeted therapy is the most effective treatment for patients with a positive BRAF mutation gene. Evaluation of a concomitant myeloid neoplasm is also critical before initiating targeted therapies for refractory ECD.

Presyncope and Ophthalmoparesis Due to Intracranial Erdheim-Chester Disease

Introduction

An 82-year-old female presented to the emergency department with presyncope and was found to be bradycardic with proptosis and ophthalmoparesis. MRI revealed an extra-axial enhancing mass compressing the medulla and bilateral enhancing retro-orbital masses.

Case Description

Imaging, including nuclear medicine bone scan, PET CT, and cardiac MRI raised the suspicion for a histiocytic neoplasm. These findings, along with a fibrohistiocytic infiltrate on bone biopsy and a BRAF V600E oncogenic mutation on plasma cell-free DNA confirmed a diagnosis of Erdheim-Chester disease.

Discussion

These enhancing masses invoke a broad differential, including a histiocytic or granulomatous process, fungal infection, amyloidosis, IgG4 disease, and lymphoma. Systematic laboratory, radiologic, pathology, and genetic testing yielded a diagnosis of this rare histiocytic disorder with frequent neurologic involvement.

A Rare Cause of Abdominal Pain: Erdheim-Chester Disease

A 65-year-old man presented with hematuria, night sweats, nausea, intermittent nonbloody diarrhea, and abdominal pain. Computed tomography angiogram with enterography showed retroperitoneal fibrosis surrounding both kidneys and ureters without any evidence of vascular obstruction or hydronephrosis. Laparoscopic biopsy demonstrated fibroadipose tissue involved by a subtle histiocytic infiltrate in a background of marked fibrosis, scattered lymphocytes, and plasma cells. The histiocytes strongly expressed CD163, Factor XIIIa, and BRAF V600E. He was diagnosed with Erdheim-Chester disease, a rare histiocytic neoplasm uncommonly presenting with gastroenterological manifestations.

Imaging Phenotypes and Evolution of Hepatic Langerhans Cell Histiocytosis on CT/MRI: A Retrospective Study of Clinical Cases and Literature Review

(1) Background: pathological changes in hepatic Langerhans cell histiocytosis (LCH) have been observed; however, corresponding imaging findings can appear vague to physicians and radiologists. The present study aimed to comprehensively illustrate the imaging findings of hepatic LCH and to investigate the evolution of LCH-associated lesions. (2) Methods: LCH patients with liver involvement treated at our institution were retrospectively reviewed along with prior studies in PubMed. Initial and follow-up computed tomography (CT) and magnetic resonance imaging (MRI) were systematically reviewed, and three imaging phenotypes were created based on the lesion distribution pattern. Clinical features and prognoses were compared among the three phenotypes. Liver fibrosis was evaluated visually on T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI), and apparent diffusion coefficient (ADC) values of the fibrotic areas were measured. Descriptive statistics and a comparative analysis were used to analyze the data. (3) Results: based on the lesion distribution pattern on CT/MRI scans, patients with liver involvement were categorized as the disseminated lesion phenotype, scattered lesion phenotype, and central periportal lesion phenotype. Patients with scattered lesion phenotype were typically adults, and only a few of them had hepatomegaly (n_present = 1, 1/6, 16.7%) and liver biochemical abnormalities (n_present = 2, 2/6, 33.3%); patients with central periportal lesion phenotype were typically young children, and hepatomegaly and biochemical abnormalities were more apparent in these patients than those with another phenotype; and those with the disseminated lesion phenotype were found in all age groups, and the lesions evolved rapidly on medical imaging. Follow-up MRI scans show more details and can better document the evolution of lesions than CT. T2-hypointense fibrotic changes, including the periportal halo sign (n_present = 2, 2/9, 22.2%), patchy liver parenchyma changes (n_present = 6, 6/9, 66.7%), and giant hepatic nodules close to the central portal vein (n_present = 1, 1/9, 11.1%), were found, while fibrotic changes were not observed in patients with the scattered lesion phenotype. The mean ADC value for the area of liver fibrosis in each patient was lower than the optimal cutoff for significant fibrosis (METAVIR Fibrosis Stage ≥ 2) in a previous study that assessed liver fibrosis in chronic viral hepatitis. (4) Conclusions: The infiltrative lesions and liver fibrosis of hepatic LCH can be well characterized on MRI scans with DWI. The evolution of these lesions was well demonstrated on follow-up MRI scans.

The value of 18F-FDG PET/CT in the systemic evaluation of patients with Rosai-Dorfman disease: a retrospective study and literature review

BACKGROUND

Rosai-Dorfman disease (RDD) is a rare form of non-Langerhans cell histiocytic disease. The aim of this study was to review the characteristics of RDD using ¹⁸F-FDG PET/CT and determine its efficacy in the disease management.

RESULTS

A total of 28 RDD patients underwent 33 ¹⁸F-FDG PET/CT scans for systematic assessment and follow-up. The common involved sites included the lymph nodes (17, 60.7%), upper respiratory tract (11, 39.3%), and skin (9, 32.1%). Five patients had more lesions detected in PET/CT images than in CT and/or MRI, including inapparent nodules (n = 5) and bone destruction (n = 3). After thorough treatment evaluation using PET/CT, the treatment strategies of 14 patients (14/16, 87.5%) were changed. Five patients underwent PET/CT twice during follow-up and the SUVs were significantly decreased (15.3 ± 3.4 vs. 4.4 ± 1.0, p = 0.02), which demonstrated disease improvement.

CONCLUSIONS

¹⁸F-FDG PET/CT contributed to displaying the holistic characteristics of RDD, in particular during initial assessment, treatment strategy adjustment, or efficacy evaluation, and could compensate for some disadvantages of CT and MRI images.

How I Diagnose Rosai-Dorfman Disease

OBJECTIVES

Rosai-Dorfman disease (RDD) is one of 3 major types of histiocytosis, along with Erdheim-Chester disease and Langerhans cell histiocytosis. While historically, RDD was considered a benign self-limited condition, current data show MAPK/ERK pathway mutations in 30% to 50% of cases, indicative of a clonal process. Rosai-Dorfman disease was incorporated as a histiocytic neoplasm in the fifth edition of the World Health Organization classification of hematopoietic tumors and the International Consensus Classification.

METHODS

We discuss the diagnosis of RDD using 2 illustrative cases, interpretative challenges, and a diagnostic algorithm.

RESULTS

Rosai-Dorfman disease involves nodal and extranodal sites, including skin, sinuses, salivary gland, orbit, central nervous system, kidney, and bone. In a subset, RDD can coexist with other neoplasms (lymphomas, other histiocytosis) or autoimmune disease. Morphologically, RDD histiocytes are characterized by enlarged round to oval nuclei, distinct nucleoli, and voluminous cytoplasm with engulfment of inflammatory cells (emperipolesis). By immunohistochemistry, they express CD68, CD163 (majority), S100, OCT2, and cyclin D1. Appropriate use of ancillary studies is important to support the diagnosis of RDD while excluding other histiocytic neoplasms and reactive histiocytic proliferations.

CONCLUSIONS

Management of RDD is dependent on the extent of organ involvement and clinical symptoms. In patients who require therapy, next-generation sequencing is recommended to identify MAPK/ERK pathway mutations for targeted therapy.

Primary diffuse Rosai-Dorfman disease in central airway: a case report and literature review

BACKGROUND

Rosai-Dorfman disease (RDD) is a rare benign non-langerhans cell histiocytosis, mainly involving lymph nodes and skin. It is even rarer occurring only in central airway of lung and in diffuse form. Central airway RDD is similar to malignant tumor in imaging by radiological method and in bronchoscopy features. It is difficult to differentiate it from primary airway malignant tumor and to diagnose correctively in time.

CASE PRESENTATION

Here we present a rare case of 18-year-old male diagnosed with primary diffuse RDD in central airway. Although the features examined by enhanced chest computed tomography, positron emission tomography/computed tomography, diffusion-weighted imaging of enhanced chest MRI and bronchoscopy indicate to be malignant tumor, the patient was definitely confirmed by multiple transbronchial biopsies and immunohistochemistry. After two transbronchial resections, the patient's symptoms of paroxysmal cough, whistle sound and shortness of breath were significantly reduced, as well as the airway stenosis was significantly improved. After 5 months of follow-up, the patient had no symptoms and the central airway were unobstructed.

CONCLUSIONS

Primary diffuse RDD in central airway is characterized by intratracheal neoplasm, which is usually suspected as malignant tumor according to radiological image and bronchoscopy. Pathology and immunohistochemistry are necessary for definite diagnosis. Transbronchial resection is effective and safe for patients with primary diffuse RDD in central airway.

Nasal Presentations of Rosai-Dorfman Disease: Clinical Manifestation and Treatment Outcomes

PURPOSE

There has been a lack of evidence-based management strategies on the nasal presentations of Rosai-Dorfman disease (RDD). We aim to investigate the clinical manifestation, treatment, and outcomes in patients with nasal RDD.

METHODS

We retrospectively reviewed available medical records of patients diagnosed with nasal RDD from 2014 to 2021 at our department.

RESULTS

A total of 26 patients were included with a marked female preponderance (2.25:1). The most common symptom and affected sites were nasal congestion (31%) and nasal cavity (73%), respectively. The average times of biopsies was 1.5 times (range: 1-3). The histiocytes were positive about S100 and CD68 and negative for CD1a with common emperipolesis. The mean duration of follow-up was 34 months (range, 3-87). One patient with concomitant nasal small B-cell lymphoma achieved complete remission after chemoradiotherapy. Recommended treatments were endoscopic resection (92%) and oral corticosteroids (21%). Surgery was performed to remove the resectable lesion as completely as possible. Corticosteroids induced almost 100% overall remission. Of the relapses, two patients achieved an overall response and one remained in progressive stage after subsequent excision. Two patients only received dissection biopsy that responded to oral corticosteroid administration and combined therapies of lenalidomide and dexamethasone, respectively.

CONCLUSIONS

Diffuse lesions in nasal cavity and sinuses, and even widely affected nasal skull base, laryngopharynx, orbit, and cavernous sinus, should be considered the possibility of Rosai-Dorfman disease. Characteristic immunohistochemical staining is helpful for the diagnosis. Endoscopic surgical therapy remains the mainstream treatment for patients enduring an unbearable course. Oral corticosteroid administration serves as an adjuvant therapy for first-line treatments.

Erdheim-Chester disease: A multisystem disease case illustration with rare manifestations and treatment challenges

Erdheim-Chester disease is a rare multisystemic disease. A 50-year-old woman, presented with a recurrent pain and swelling of the left knee. Bone scintigraphy showed increased tracer uptake of peripheral skeleton. The computed tomography showed tissular infiltration in the retroperitoneum, around the vessels. Immunohistochemistry showed CD68 (+) and CD1a (-).

Erdheim-Chester disease with Rosai-Dorfman-like lesions: treatment with methotrexate, anakinra and upadacitinib

Erdheim-Chester disease (ECD) is a non-Langerhans cell histiocytosis characterised by clonal expansion of histiocytes in various organs. These induce an inflammatory environment, which leads to damage of the affected areas. Recently, a new disease entity was proposed encompassing key features of ECD but also of Rosai-Dorfman-Destombes disease, another histiocytosis. Mitogen-activated protein kinase kinase 1 (MAP2K1) mutations seem to present a specific genetic lesion for this subtype.Here, we describe a case of this new disease entity with clinical, radiological and genetic findings compatible with ECD but histological findings compatible with Rosai-Dorfman-Destombes disease. In particular, there were intraabdominal and retroperitoneal lesions, which tested positive for a (c.167A>C; p.Q56P) mutation of the MAP2K1 gene. On histological examination, S100-positive, giant histiocytes with focal emperipolesis of haematological cells in addition to infiltration by lymphocytes and granulocytes were seen.As described for this rare variant of ECD, there was also bilateral testicular infiltration. We also describe a manifestation of oligoarthritis in this patient with ECD.The patient was treated with methotrexate and prednisolone. While radiological response to this regime was excellent, arthritis persisted. We added anakinra, which induced a response of the arthritis for more than a year. Due to treatment failure therapy was switched to upadacitinib, which induced a remission of the arthritis as well.This case adds a rare phenotype to an already rare presentation of ECD. The patient responded to immunosuppressive therapy.

Ophthalmologic Involvement in Adults with Histiocytic Disorders: Clinical Presentation and Treatment Outcomes

PURPOSE

To evaluate the clinical presentation, treatment, and outcomes in adult patients with histiocytic disorders with ocular, orbital, optic nerve, or cavernous sinus involvement.

DESIGN

Observational, retrospective chart review.

PARTICIPANTS

Adult patients (age ≥ 18 years) at Mayo Clinic from January 1, 1996, to July 1, 2021, with histiocytic disorders. Inclusion criteria were (1) histiocytic disorder by biopsy and appropriate clinical phenotype; (2) available medical records; and (3) ocular, orbital, optic nerve, or cavernous sinus involvement.

METHODS

Retrospective chart review.

MAIN OUTCOME MEASURES

Response to therapy, measured in clinical and radiographic impact.

RESULTS

Thirty-two patients were identified: 7 with Langerhans cell histiocytosis (LCH); 15 with Erdheim-Chester disease (ECD); 1 with mixed LCH/ECD phenotype; 8 with Rosai-Dorfman disease (RDD); and 1 with mixed RDD/ECD phenotype. Ophthalmologic involvement was part of the initial presentation in 69% of patients (22/32). Eyelid edema (13/32, 41%) and proptosis (12/32, 38%) were the most frequent presentations. Isolated orbital or cavernous sinus involvement was present in 3 of 7 patients with LCH and 1 of 8 patients with RDD. Optic nerve sheath involvement was present in 2 of 7 LCH patients, 14 of 15 ECD patients, and 1 RDD/ECD patient. Diffuse (> 75%) orbital involvement was seen in 12 of 15 ECD patients and 1 of 7 LCH patients. Ocular involvement was seen in 1 of 15 ECD patients, 6 of 8 RDD patients, and 1 of 1 mixed RDD/ECD patient. The cavernous sinuses were involved in 1 of 7 LCH patients, 5 of 15 ECD patients, and both mixed phenotype patients. Visual acuity was affected in 14 patients (14/24, 58%) with a median logarithm of the minimum angle of resolution visual acuity of 0.1 (range, -0.12 to 3). BRAF V600E mutations were found in 75% (3/4) of LCH patients and 91% (10/11) of ECD patients. Patients received a variety of treatment, and response was variable across disease types.

CONCLUSIONS

Orbital involvement was more commonly seen in LCH and ECD, whereas ocular involvement was more common in RDD. Visual acuity may be impacted from ocular involvement or compression of the optic nerve with diffuse orbital involvement.

Erdheim-Chester Disease Involving the Central Nervous System with Latent Toxoplasmosis

Erdheim-Chester disease (ECD) is a rare, non-Langerhans cell histiocytosis characterized by the infiltration of foamy histiocytes into multiple organs. We herein report a case of ECD with central nervous system (CNS) involvement in a 63-year-old man who also presented a positive result for Toxoplasma gondii nested polymerase chain reaction testing of cerebrospinal fluid. Since anti-Toxoplasma treatment proved completely ineffective, we presumed latent infection of the CNS with T. gondii. This case suggests the difficulty of distinguishing ECD with CNS involvement from toxoplasmic encephalitis and the possibility of a relationship between the pathogeneses of ECD and infection with T. gondii.

Application of 18F-FDG PET/CT in Langerhans Cell Histiocytosis

Purpose

This study aims to explore the application value of the ¹⁸F-FDG PET/CT imaging in diagnosing, staging, and typing Langerhans cell histiocytosis (LCH) via the morphological and metabolic analyses of the ¹⁸F-FDG PET/CT images.

Methods

We retrospectively analyzed the ¹⁸F-FDG PET/CT images and clinical data of nineteen patients with LCH. The shape, size, density, distribution, and ¹⁸F-FDG uptake of all lesions were documented. In addition, the SUVmax of the lesions, liver, and blood pool was measured prior to calculating the lesion-to-liver and lesion-to-blood pool ratios.

Results

Among the 19 analyzed patients, the positive rate of the PET/CT image was 94.7% (18/19), with 1 false negative (5.3%, 1/19) case occurring in the cutaneous LCH. Among the 76 lesions, 69 were FDG-avid lesions (69/76, 90.8%). Additionally, we observed no FDG uptake in 7 lesions (7/76, 9.2%). In contrast, 59 lesions (59/76, 77.6%) were abnormal on diagnostic CT scan, but 17 lesions (17/76, 22.4%) were undetected. The ¹⁸F-FDG PET/CT image revealed additional 6 lesions in the bone, 4 in the lymph node, 3 in the spleen, and 3 occult lesions, which CT scan did not detect. Additionally, there were 6 cases with single-system LCH. The remaining 13 cases were multisystem LCH. Our ¹⁸F-FDG PET/CT image analyses altered the typing of 4 LCH patients. In the case of all lesions, the mean SUVmax of the ¹⁸F-FDG-avid lesions was 5.4 ± 5.1 (range, 0.8∼26.2), and the mean lesion-to-liver SUVmax ratio was 3.1 ± 2.52 (range, 0.7∼11.9), and the mean lesion-to-blood pool SUVmax ratio was 4.6 ± 3.4 (range 0.7∼17.5).

Conclusion

The ¹⁸F-FDG PET/CT image plays an essential role in LCH diagnosis, primary staging, and typing. It can accurately evaluate the distribution, range, and metabolic information of LCH, providing a vital imaging basis for the clinical evaluation of disease conditions, selection of treatment schemes, and determining patient prognosis.

FDG PET/CT in Mixed Langerhans Cell Histiocytosis and Erdheim-Chester Disease

ABSTRACT

The histiocytoses arise from hematopoietic bone marrow stem cells or monocytes. They range from limited to disseminated disease. We report a 31-year-old woman with multisystem Langerhans cell histiocytosis (LCH). The recognition that pericardial disease was rare in LCH prompted review of the initial limited biopsies, which helped establish a second diagnosis of Erdheim-Chester disease. The increasing recognition of mixed histiocytoses requires searching for Erdheim-Chester disease when a patient is diagnosed with LCH and vice versa. FDG PET/CT can help establish the diagnosis or suggest mixed disease based on the organs involved.

Extensive fibrotic wrapping of the heart: a rare echocardiographic diagnosis

BACKGROUND

Fibrosing mediastinitis (FM) is considered a benign disease, but it can be fatal if progression leads to compression of the hilum of the lungs or invasion of the heart. Echocardiographic reports of this disease are very rare.

CASE PRESENTATION

We present a 14-year-old male patient whose non-enhanced chest computed tomography showed unclear soft-tissue dense lesions in the anterior superior mediastinum. Echocardiography showed the heart was extensively wrapped by soft tissue lesions. The histology confirmed FM.

CONCLUSIONS

When FM affects the heart, echocardiography can help to characterize the disease and aid in the diagnosis. Echocardiography should be considered an important tool to follow the progression of this disease and guide the therapeutic approach.

Pancreatic involvement in Erdheim-Chester disease: a case report and review of the literature

Background

Erdheim-Chester disease (ECD) is a rare form of non-Langerhans cell histiocytosis characterized by infiltration of lipid-laden foamy macrophages within different tissues. Clinical manifestations of ECD are highly heterogeneous. Bone lesions are found in 80%-95% of patients, while extraosseous lesions usually involve the cardiovascular system, retroperitoneum, central nervous system (CNS), and skin. Pancreatic involvement in ECD has barely been reported.

Case presentation

A 29-year-old female initially presented with menoxenia, diabetes insipidus and diabetes mellitus. 18F-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG-PET/CT) revealed hypermetabolic foci in the bilateral frontal lobe, saddle area, and pancreas. A 99mTc-MDP bone scrintigraphy scan revealed symmetrical increased uptake in distal femoral and proximal tibial metaphysis, which was confirmed to be osteosclerosis by high-resolution peripheral quantitative computed tomography. The patient underwent incomplete resection of the sellar mass. Histological examination of biopsies showed histiocytic aggregates, which were positive for S100 and negative for CD1a and CD207 on immunohistochemistry. Enhanced abdominal CT scan showed hypointense nodules within the body and tail of the pancreas. Endoscopic ultrasonography guided fine-needle aspiration (EUS-FNA) found no evidence of malignancy. She was diagnosed with ECD and treated with high-dose IFN-α. Repeated examinations at three-and eight-months post treatment revealed markedly reduction of both intracranial and pancreatic lesions.

Conclusions

ECD is a rare histiocytic neoplasm that can involve almost every organ, whereas pancreatic involvement has barely been reported to date. Here, we present the rare case of pancreatic lesions in ECD that responded well to interferon-α. We further reviewed reports of pancreatic involvement in histiocytic disorders and concluded the characteristics of such lesions to help diagnosis and treatment, in which these lesions mimicked pancreatic adenocarcinoma and caused unnecessary invasive surgeries.

International expert consensus recommendations for the diagnosis and treatment of Langerhans cell histiocytosis in adults

Langerhans cell histiocytosis (LCH) can affect children and adults with a wide variety of clinical manifestations, including unifocal, single-system multifocal, single-system pulmonary (smoking-associated), or multisystem disease. The existing paradigms in the management of LCH in adults are mostly derived from the pediatric literature. Over the last decade, the discovery of clonality and MAPK-ERK pathway mutations in most cases led to the recognition of LCH as a hematopoietic neoplasm, opening the doors for treatment with targeted therapies. These advances have necessitated an update of the existing recommendations for the diagnosis and treatment of LCH in adults. This document presents consensus recommendations that resulted from the discussions at the annual Histiocyte Society meeting in 2019, encompassing clinical features, classification, diagnostic criteria, treatment algorithm, and response assessment for adults with LCH. The recommendations favor the use of 18F-Fluorodeoxyglucose positron emission tomography-based imaging for staging and response assessment in the majority of cases. Most adults with unifocal disease may be cured by local therapies, while the first-line treatment for single-system pulmonary LCH remains smoking cessation. Among patients not amenable or unresponsive to these treatments and/or have multifocal and multisystem disease, systemic treatments are recommended. Preferred systemic treatments in adults with LCH include cladribine or cytarabine, with the emerging role of targeted (BRAF and MEK inhibitor) therapies. Despite documented responses to treatments, many patients struggle with a high symptom burden from pain, fatigue, and mood disorders that should be acknowledged and managed appropriately.

Langerhans Cell Histiocytosis Involving the Thymus and Heart With Simultaneous Thymoma: A Case Report

Langerhans cell histiocytosis (LCH) is a rare disease characterized by clonal expansion of CD1a+/CD207+ cells in lesions. The most frequent sites involved are bone and, less commonly, lymph nodes, lungs, and skin. The thymus or heart is rarely involved with LCH. In this case, we present a 73-year-old woman with a mediastinal mass. Histopathology after thymectomy identified this mass as type AB thymoma; notably, subsequent immunohistochemical tests showed lesions of LCH scattered in the region of thymoma. 18-Fluorodeoxyglucose PET/CT (18-FDG-PET/CT) was performed to make an overall assessment of the extent of this disease, which demonstrated suspicious cardiac involvement of LCH. This report highlights the importance of differentiating abnormalities of the thymus or mediastinal mass from LCH and the necessity of comprehensive evaluation for patients with LCH.

Paediatric Erdheim-Chester Disease in the Lateral Ventricle: A Case Report and Review of the Literature

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis caused by the expression of CD68-positive and CD1a-negative foam tissue cells, which is polar in pediatric patients. The study reports a case of an 8-year-old Chinese boy who presented with polydipsia and polyuria for 4 years, followed by central nervous system symptoms. Magnetic resonance imaging (MRI) showed a large lesion in the lateral ventricle. The histiocytes stained positively for CD68, CD163 and negatively for CD1a, glial fibrillary acidic protein (GFAP) and langerin, and were partially positive for S100 by immunohistochemical assay. More importantly, BRAFV^600E staining was positive in tissue, and the BRAF^V600E mutations was also detected by real-time quantitative PCR (RT-qPCR) in the intracranial lesion tissue. According to our review of the literature, this is a rare case of ECD in the ventricle, with a younger age.

Erdheim-Chester disease: a rare cause of bilateral renal artery stenosis, mimicking large vessel vasculitis

A man in his 50s with resistant hypertension and history of Langerhans cell histiocytosis (LCH) was referred to rheumatology after suspicion of inflammatory arteritis was raised. This followed detection of bilateral renal artery stenosis during investigation for severe hypertension refractory to medical therapy. CT angiography revealed diffuse wall thickening of the abdominal aorta, in keeping with an aortitis. However, there was no serological or clinical evidence suggestive of a vasculitic process. Medical history included cranial diabetes insipidus, subclavian artery stenosis and spinal stenosis requiring surgery, over the course of 8 years. These findings led to consideration of Erdheim-Chester disease (ECD), a form of non-Langerhans cell histiocytosis, where there is abnormal proliferation of histiocytes which causes tissue fibrosis and sclerosis of the long bones. Subsequent plain radiographs of the long bones revealed appearances consistent with a diagnosis of ECD. Thus, a diagnosis of an LCH/ECD overlap syndrome was made.

Rosai-Dorfman disease with spine involvement: A case report

RATIONALE

Rosai-Dorfman disease (RDD) is a rare, benign, self-limiting disease, also known as sinus histiocytosis with giant lymphadenopathy. Skeletal involvement is rare, and this isolated bone lesion usually occurs in adults with no other symptoms. It is estimated that 0.6% to 1% of RDD cases have isolated or complicated spinal lesions, which may occur in the bone, dura, and spinal parenchyma, but spinal RDD has no pathologic clinical or imaging features.

PATIENT CONCERNS

A 25-year-old woman presented with complaints of low back pain without obvious causes for a month.

DIAGNOSIS

RDD with spinal involvement.

INTERVENTIONS

Resection of the spinous process of the third lumbar spine was performed under epidural anesthesia.

OUTCOMES

At the time of discharge, the patient had no problems with autonomous activities and reported no discomfort. We also followed up the patient at 12 and 36 months after surgery, and the patient reported no discomfort, inconvenience, and no recurrence of symptoms. Imaging examination 1 year after surgery showed no recurrence.

LESSON

This case suggests that surgery for RDD with spinal involvement may not require internal fixation.

Multi-System Langerhans Cell Histiocytosis as a Mimic of IgG4-Related Disease: A Case Report and Literature Review

Langerhans cell histiocytosis (LCH) is a rare disease characterized by the clonal accumulation and/or proliferation of specific dendritic cells resembling normal epidermal Langerhans cells (LCs). Clinical manifestations are variable, depending on the affected tissues or organs, however, LCH with elevated serum IgG4 has not been reported. Herein, we reported a 26-year-old Chinese female multi-system LCH (MS-LCH) who first presented with central diabetes insipidus (CDI), accompanied by panhypopituitarism and hepatic dysfunction. Diagnostic investigations were strongly suspicious of IgG4-RD because of elevated serum IgG4 levels during the process. Furtherly, thyroid and lymph node involvement and biopsy led to the diagnosis of MS-LCH; the strongly positive staining of CD1a, S100, CD207 (langerin), and Ki67 was found. Moreover, after systemic treatment with five cycles of chemotherapy, many lesions were greatly improved. Since both LCH and IgG4-RD are orphan diseases that can affect any organ, the differential diagnosis is challenging, especially when LCH is associated with unexplained serum IgG4 elevation. In this article, the case of a young woman suffering from MS-LCH that affected organs including the pituitary, thyroid, lymph node, and liver was summarized, and relevant literature was reviewed to better equip the diagnosis and treatment in its early stages.