Rosai-Dorfman disease in neuroradiology: imaging findings in a series of 10 patients. AJR Am J Roentgenol. 2011;196:W187-W193. [PMID: 21257861 DOI: 10.2214/ajr.10.4778]

A Case of Nasal Cavity and Laryngeal Involvement of Rosai-Dorfman Disease

Rosai-Dorfman disease (RDD) is a rare non-malignant disorder, characterized by painless multiple cervical lymphadenopathy, fever, and elevated inflammatory markers. Its diagnosis is difficult due to its rare incidence and various clinical presentations, especially in extranodal involvement. In this report, we demonstrate a patient with RDD who presented with a nasal septum and laryngeal tumor that caused dyspnea. We achieved a successful treatment outcome with combined surgical resection of the laryngeal mass and corticosteroid medication. The symptoms and tumors were resolved within 3 weeks after treatment. We reported our experiences with review of literatures.

Thymic Rosai-Dorfmann disease: a case report

BACKGROUND

Rosai-Dorfman disease (RDD), known as sinus histiocytosis with massive lymphadenopathy, commonly involves lymph nodes in the neck or mediastinum, although extranodal involvement is observed in approximately 40% of RDD patients. RDD involving only the thymus has rarely been reported. Here, we report a case of RDD originating in the thymus. The lesion was surgically removed, and a cure was finally achieved. There was no recurrence after telephone follow-up for 3 years.

CASE PRESENTATION

A 52-year-old male was accidentally found to have a 7 × 6 cm anterior mediastinum lump by chest computed tomography (CT). The mediastinal lesion was resected by surgery, and postoperative pathology revealed RDD originating from the thymus. Regular telephone follow-up after surgery lasted 3 years and showed that the patient remained in good condition without any relevant symptoms.

CONCLUSIONS

RDD originating in the thymus cannot be characterized from CT images and is easily misdiagnosed as a traditional mediastinal tumor. This is mainly because there is so little disease in this area that physicians are not aware of it. We report this case with the hope that clinicians will have a better understanding of this disease. According to our follow-up results, surgery is an effective means of treatment.

Immune-Mediated Hypertrophic Pachymeningitis and its Mimickers: Magnetic Resonance Imaging Findings

Hypertrophic pachymeningitis (HP) is a rare and chronic inflammatory disorder presenting as localized or diffuse thickening of the dura mater. It can be idiopathic or an unusual manifestation of immune-mediated, infectious, and neoplastic conditions. Although some cases may remain asymptomatic, HP can lead to progressive headaches, cranial nerve palsies, hydrocephalus, and other neurological complications, which makes its recognition a fundamental step for prompt treatment. Regarding the diagnosis workup, enhanced MRI is the most useful imaging method to evaluate dural thickening. This article addresses the MR imaging patterns of immune-mediated HP, including immunoglobulin G4-related disease, neurosarcoidosis, granulomatosis with polyangiitis, rheumatoid pachymeningitis, and idiopathic HP. The main infectious and neoplastic mimicking entities are also discussed with reference to conventional and advanced MR sequences.

Primary unifocal thymic Rosai-Dorfman disease: an extremely rare challenge in diagnostic practice

Rosai-Dorfman disease (RDD) is currently considered a group of neoplastic diseases of unknown etiology, with monoclonal proliferation of histiocytes, showing unique histopathologic features and varying clinical presentation. Primary thymic RDD is an extremely rare extranodal form of this disorder. In this study, we describe the case of an otherwise healthy 64-year-old Chinese man who presented with an isolated, asymptomatic soft tissue density lesion in the anterior mediastinum detected by computed tomography. Histology of the surgical specimen revealed infiltration of thymic tissue by sheets of large histiocytes with mixed lymphocytes and plasma cells, and background fibrosis. Immunohistochemical staining of the histiocytes was positive for S100, CD68, CD163, OCT2 and cyclin D1, but negative for CD1a and BrafV600E expression, thus supporting a diagnosis of RDD. Primary thymic RDD is extremely rare and may be a diagnostic challenge when presenting as mediastinal lesion.

Temporal bone manifestation of primary extranodal Rosai-Dorfman disease: a case report

BACKGROUND

Rosai-Dorfman disease is a rare benign histiocytic disorder characterized in most cases by painless cervical adenopathy. Less than 10% of extranodal cases involve bony lesions. Primary bone Rosai-Dorfman disease in the absence of nodal disease is extremely rare.

CASE PRESENTATION

A 48 year-old Caucasian male presented with progressive right-sided otalgia, tinnitus, vertigo, and hearing loss. A right temporal bone lytic lesion was detected on diagnostic imaging. Resection of the lesion and histopathological examination revealed Rosai-Dorfman disease.

CONCLUSIONS

Rosai-Dorfman disease primary bone lesions are an atypical presentation of a rare disease. This is the second reported case of Rosai-Dorfman disease arising within the temporal bone. This case study reveals that Rosai-Dorfman disease should be considered for patients presenting with inflammatory/lytic lesions of the temporal bone, in cases where infection and malignancy have been excluded.

Synchronous Mediastinal and Central Nervous System Involvement in Rosai-Dorfman Disease: A Case Report

Rosai-Dorfman disease (RDD) is a rare disorder characterized by the proliferation and accumulation of histiocytes, primarily within lymph node sinuses. Uncommonly, other extranodal sites, such as the central nervous system, can also be affected. Here, we document the case of a 61-year-old woman presenting with dizziness, confusion, and headaches. Magnetic resonance imaging (MRI) showed an extra-axial avidly enhancing mass in the left parietal region presumed to be a meningioma based solely on its imaging appearance. The patient underwent surgical resection, and histopathological examination showed enlarged histiocytes positive for S100, CD68, and CD163 and negative for CD1a, consistent with RDD. She was followed up with a positron emission tomography/computed tomography (PET/CT) to evaluate other disease activity sites. A single mediastinal node was identified adjacent to the atriocaval junction intensely fluorodeoxyglucose avid. The patient underwent robotic node excision, with pathology analysis compatible with RDD. We emphasize the need to increase recognition of RDD on differential brain lesions, especially meningiomas, and suggest PET/CT as a valid tool to search for other disease activity lesions.

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.

Rosai-Dorfman Disease in the Skull Base: A Case Series Study

OBJECTIVE

Rosai-Dorfman disease (RDD) is a rare, idiopathic, and non-neoplastic histio-proliferative disease that is uncommon in the central nervous system. Hence, reports of management of RDD in the skull base are scarce and only a few studies on skull base RDD are available. The objective of this study was to analyze the diagnosis, treatment, and prognosis of RDD in the skull base and explore an appropriate treatment strategy thereof.

METHODS

Nine patients with clinical characteristics and follow-up data from our department between 2017 and 2022 were included in this study. From this information, the clinical profiles, imaging, treatment, and prognosis data were collected.

RESULTS

There were 6 male and 3 female patients with skull base RDD. These patients ranged in age from 13 to 61 years, with a median age of 41 years. The locations included 1 anterior skull base orbital apex, 1 parasellar region, 2 sellar regions, 1 petroclivus, and 4 foramen magnum regions. Six patients underwent total resection and 3 underwent subtotal resection. Patient follow-up lasted 11-65 months, with a median duration of 24 months. One patient died, 2 experienced recurrence, and the other patients' lesions were stable. The symptoms worsened and new complications occurred in 5 patients.

CONCLUSIONS

Skull base RDDs are intractable diseases with a high rate of complications. Some patients are at risk of recurrence and death. Surgery may be the basic treatment for this disease, and combined therapy including targeted therapy or radiation therapy may also be a valuable therapeutic strategy.

A case report of epileptic seizures caused by Rosai Dorfman disease followed by a literature review

RATIONALE

Rosai Dorfman disease is a rare benign histiocytoproliferative disorder that occurs in the intracranial area, which occurrs typically in lymph nodes. Extrapnodal Rosai Dorfman disease rarely develops in the central nervous system and is often a focal lesion based on the dura. Based on imaging and clinical symptoms, RDD may be misdiagnosed as meningioma, and some lesions can also occur in the brain parenchyma. In the case of benign disease, the final diagnosis is made by pathological tissue diagnosis. For chronic diseases, progression may be chronic or remitting and relapsing.

PATIENT CONCERNS

A 54-years-old man was hospitalized after experiencing paroxic convulsions and being unconsciousness. A head magnetic resonance imaging demonstrates a strip of lesions in the right parietal lobe. No obvious abnormality is found in the laboratory data.

DIAGNOSES

We diagnosed meningioma of right parietal lobe and secondary epilepsy, and prescribed oral sodium valproate to treat him.

INTERVENTIONS

The lesion is located in the right parietal lobe on neuroimaging prior to surgery, which was taken for immunohistochemical examination.

OUTCOMES

If it is found that immunohistochemistry reveals histiocytes are positive for CD68, S-100, but negative for CD1a, it is identified as RDD. For patients who are seizure-free following surgery, symptomatic management is used. Following parietal lesion resection, patients are seizure-free during the follow-up period (44 months).

LESSONS

Basing on studying and summarizing relevant literatures, RDD is described in the report in terms of its diagnosis, pathology, treatment, and clinical outcome, in order to improve the diagnosis and identification of intracranial RDD by physicians.

Intracranial Rosai-Dorfman Disease: A Case to Remember

Sinus histiocytosis with massive lymphadenopathy (SHML), an alternative term for Rosai-Dorfman disease (RDD), is a rare benign idiopathic immune-related lymphoproliferative condition. The central nervous system (CNS) has been documented to be involved in RDD, although lymph nodes are the organs that are most frequently and primarily associated with the disease manifestation. Nonetheless, CNS involvement in RDD is rare and poorly understood. As a result, there is a lack of a solid basis for therapeutic approaches for CNS involvement in RDD. Here, we present a case of RDD with cerebral involvement, a rare presentation of RDD with atypical symptoms. A brief assessment of the radiographic appearance, histological findings, and the peculiar manifestations of the disease is provided.

Intracranial Rosai Dorfman Disease Presented With Multiple Huge Intraventricular Masses: A Case Report

Introduction

Rosai-Dorfman disease (RDD) usually presents with painless cervical lymphadenopathy during the two first decades of life, with or without extranodal involvement. Exclusive extranodal manifestation, and especially central nervous system (CNS) involvement, is uncommon. The etiology remains unknown and definitive diagnosis is based on characteristic histopathological and immunohistochemical features showing S100(+) CD1a(−) RDD type histiocytes with emperipolesis. Most CNS cases are dural-based masses.

Case Presentation

Herein, we present a case of RDD in an 8-year-old boy, who presented with multiple huge intraventricular masses.

Conclusion

Regarding rare CNS involvement and lack of established evidence-based therapeutic approaches, reports of any individual case can supply further beneficial data concerning treatment approaches and long-term effectiveness of therapeutic strategies.

Staging surgery for intraventricular bilateral giant Rosai–Dorfman disease in children

Introduction

Rosai–Dorfman disease (RDD) is an uncommon, benign, and idiopathic histiocytic proliferative disorder. Multiple intracranial RDD is extremely rare and treatment varies.

Case presentation

A 9‐year‐old girl was admitted with 3‐month history of blurred vision and facial paralysis, a 2‐month history of recurrent giggle, and cognitive impairment. Computed tomography and magnetic resonance imaging scans revealed bilateral ventricular masses based on the dural membrane and the diameters of the masses were 9.1 cm and 9.2 cm, respectively. The lesions were completely removed with staging surgeries. Fifteen months after operation, blurred vision was still present but facial paralysis and giggle and cognitive impairment disappeared. Imaging examinations suggested that there were no new or recurring lesions.

Conclusion

For multiple large intracranial masses, surgical treatment is necessary and staged surgery benefits perioperative safety. Active follow‐up with magnetic resonance imaging is necessary.

Regression of Intraocular Rosai- Dorfman Disease Following Treatment with Photodynamic Therapy

Rosai-Dorfman disease (RDD), a rare form of histiocytosis, has been reported to cause choroidal masses and subsequent serous retinal detachments. We present a case of RDD associated with a choroidal mass and retinal detachment that did not respond to corticosteroid treatment and regressed after treatment with photodynamic therapy (PDT). Following treatment, the patient had a successful anatomic and clinical outcome, with no recurrence of serous detachment and 20/25 visual acuity. This is the first report of choroidal RDD successfully treated with PDT. [Ophthalmic Surg Lasers Imaging Retina. 2021;52:568-571.].

Systemic and Craniospinal Rosai Dorfman Disease with Intraparenchymal, Intramedullary and Leptomeningeal Disease

Rosai Dorfman disease is a rare histiocytic disorder of over-production of non-Langerhans histiocytes, which typically manifests with massive lymphadenopathy and sinonasal involvement. We report a rare case of systemic and disseminated craniospinal Rosai Dorfman disease with intraparenchymal and leptomeningeal involvement, but no sinus or dural-based disease. The diagnosis was established by biopsy of a hypothalamic mass. Additionally, UCSF500 Next Generation Sequencing demonstrated a solitary pathogenic alteration affecting the BRAF oncogene, which supports the morphologic and immunohistochemical diagnosis of Rosai-Dorfman disease.

Rosai-Dorfman disease mimicking images of meningiomas: Two case reports and literature review

Background:

Rosai-Dorfman disease (RDD) is a rare non-Langerhans cell histiocytic proliferative disorder classically as a massive cervical lymphadenopathy. However, over the years, extranodal locations were confirmed with the central nervous system involvement in less than 5% of cases, which is marked as a significant differential diagnosis of meningiomas, with which they are widely confused due to the similarity of their radiological images.

Case Description:

We report a 37-year-old man and 45-year-old man who were diagnosed with intracranial RDD but whose radiological images mimic meningiomas, requiring anatomopathological and tumor’s immunohistochemistry for definitive diagnosis. Moreover, a review of 184 publications with 285 cases of intracranial involvement of this disease was also performed, comparing these findings with those brought in the previous studies.

Conclusion:

Intracranial Rosai-Dorfman tumors should always be remembered as differential diagnosis of meningiomas since they are similar radiologically and macroscopically. Once remembered and diagnosed, the lesion must be treated following the same pattern of resection done in meningiomas and, treatment’s differences will not occur in the surgical excision technique, but in complementary chemotherapy implementation, radiotherapy, and even with radiosurgery aid, depending on the case. Thus, it is possible to obtain better results than with just the isolated surgical procedure.

Rosai-Dorfman disease with lung involvement in a 10-year-old patient: A case report

BACKGROUND

Rosai-Dorfman disease (RDD) is a rare benign proliferative disease whose etiology is not clear and may be related to infection or unexplained immune dysfunction. The authors present a case of RDD with lung involvement in a 10-year-old patient.

CASE SUMMARY

A 10-year-old girl found that her left cervical lymph nodes were enlarged for more than 7 mo, and the largest range was about 6.5 cm × 5.9 cm × 8.1 cm. Cervical magnetic resonance imaging showed multiple masses in the left neck, with low signal intensity on T1-weighted images and high signal intensity on T2-weighted images. A malignant tumor, with a high possibility of lymph node metastasis, was initially considered. At the same time, lung computed tomography showed multiple nodules of different sizes scattered on both sides of the lung, with uniform internal density. Thus, a possible metastatic tumor was considered. Finally, RDD was diagnosed by pathology and immunohistochemistry. According to the antibiogram, clindamycin was administered for 2 wk, and prednisone acetate was administered for 7 wk. Nine months later, the ulcer in the left neck was better than before, but the imaging showed that the lesion was not controlled.

CONCLUSION

The diagnosis of RDD cannot be made by a single tool and its treatment is a long-term exploratory process. Follow-up is necessary.

Rosai-Dorfman disease with infiltration of IgG4-bearing plasma cells presenting as laryngeal-nasal masses and cervical lymphadenopathy: A case report

RATIONALE

Rosai-Dorfman disease (RDD) is a rare and self-limiting condition caused by the non-neoplastic proliferation of histiocytes/phagocytes in the sinusoids of lymph nodes and in extranodal tissues. Of the extranodal involvement, laryngeal involvement is extremely rare. Because of its rarity and nonspecific clinicoradiologic features, RDD is often difficult to differentiate from other benign or malignant lymphoproliferative diseases. We present a case of RDD with infiltration of IgG4-bearing plasma cells manifesting laryngeal and nasal masses with cervical lymphadenopathy.

PATIENT CONCERNS

A 45-year-old male patient presented with recurrent epistaxis and airway disturbance.

DIAGNOSES

On endoscopy, there were submucosal masses in both nasal cavities and both sides of subglottic larynx. On neck CT, there were well-defined, enhancing soft tissue masses in both nasal cavities and both sides of subglottic larynx, resulting in mild airway narrowing. In addition, multiple enlarged lymph nodes showing homogeneous enhancement were noted in both parotid glands and both internal jugular chains. All lesions demonstrated marked FDG-uptake on PET/CT. Therefore, the initial radiologic differential diagnoses included lymphoma and IgG4-related disease. Biopsy was performed on the nasal and laryngeal lesions, and they revealed RDD with infiltration of IgG4-bearing plasma cells.

INTERVENTION

The patient underwent surgical resection of the masses in the nasal cavity and larynx to relieve airway narrowing.

OUTCOMES

After surgery, airway obstruction was much improved and the patient was asymptomatic. On outpatient follow-up, he exhibited a stable condition and had no dyspnea on exercise.

LESSONS

Clinical awareness and suspicion are important for the accurate diagnosis and management of patients with homogeneous masses in the larynx or nasal cavity, even if there is no combined cervical lymphadenopathy.

Spectrum of [18F]FDG-PET/CT Findings in Benign Lymph Node Pathology

Diffuse lymphadenopathy has a long differential diagnosis that includes both malignant and benign causes. As part of the lymphadenopathy work-up, many patients undergo [¹⁸F]FDG-PET/CT for purposes of ruling out malignancy. FDG-avid lymph nodes, however, are not specific for malignancy. This review will illustrate the spectrum of nodal findings on FDG-PET/CT with correlation to other cross-sectional imaging and clinical history in patients with representative infectious, inflammatory, and benign lymphoproliferative disorders. These findings are important for the nuclear medicine radiologist to understand, as they can represent common pitfalls in the work-up of lymphadenopathy. While FDG-PET/CT may be limited in ascertaining a definitive diagnosis in a disease process as the cause of lymphadenopathy, it can help to narrow this differential and rule out certain diseases in the correct clinical context.

Diagnosis and treatment of Rosai-Dorfman disease of the spine: a systematic literature review

PURPOSE

To review and summarize the clinical features, diagnosis, treatment strategies, and prognosis of spinal Rosai-Dorfman disease (RDD).

METHODS

RDD is also termed as sinus histiocytosis with massive lymphadenopathy. We searched the databases of PubMed, Elsevier ScienceDirect, SpringerLink, and OVID. The keywords were Rosai-Dorfman disease and spine/central nervous system. Research articles and case reports with accessibility to full texts regarding spinal RDD were eligible for the inclusion. A total of 62 articles were included, and they contained 69 cases. We extracted the information of interest and analyzed them using SPSS statistics package.

RESULTS

The average age was 33.1 ± 18.3 years. The ratio of males to females was 1.9/1. Overall, 63 cases presented with spine-related symptoms. A total of 27 cases (39.1%) had multi-organ lesions, and 12 cases had records of massive lymphadenopathy. Among 47 cases who first manifested spine-related symptoms, 93.6% were preoperatively misdiagnosed. The disease had a predilection for cervical spine (38.8%) and thoracic spine (40.3%). 62.9% of lesions were dura-based. Surgery remained the mainstream treatment option (78.8%), with or without adjuvant therapies. Total lesion resection was achieved in 34.8% of cases. The rate of lesion recurrence/progression was 19.5%, which was marginally lower for total resection than for non-total resection.

CONCLUSION

Spinal RDD has no pathognomonic clinical and imaging features. Most cases first present with spine-relevant symptoms. Massive lymphadenopathy is not common, but a tendency for multi-organ involvement should be considered. Spinal RDD has a high recurrence rate; thus, total resection is the treatment of choice. Adjuvant therapies are indicated for multi-organ lesions and residual lesions. A wait and watch strategy is recommended for asymptomatic patients. Herein, a workflow of diagnosis and treatment of the spinal RDD is established.

MRI features of intra-axial histiocytic brain mass lesions

AIM

To describe MRI features, including diffusion-weighted imaging (DWI), magnetic resonance spectroscopy (MRS), and perfusion-weighted imaging (PWI), of intra-axial tumour-like presentations of four different subtypes of histiocytosis.

MATERIAL AND METHODS

The brain MRI findings of 23 patients with histologically proven histiocytosis were reviewed retrospectively (11 Langerhans cell histiocytosis [LCH], eight Erdheim-Chester disease [ECD], one overlap form LCH/ECD, two Rosai-Dorfman disease [RDD], and one haemophagocytic lymphohistiocytosis [HLH]) with single or multiple enhancing intraparenchymal brain lesions.

RESULTS

Histiocytic brain mass lesions show some similar MRI features including Supra and/or infratentorial and/or paraventricular subcortical well-delineated masses, linear ependymal enhancement along the ventricles and brain stem lesions. Masses always present with mixed hyper- and hypointense signal on T2-weighted imaging (WI). Their enhancement is often homogeneous. Apparent diffusion coefficient (ADC) values are often normal or elevated.

CONCLUSION

The presence of multiple periventricular and subcortical enhancing lesions with mixed signal intensity on T2WI and normal or high ADC values should lead radiologists to consider the diagnosis of histiocytic lesions and search for associated systemic lesions.

Rosai-Dorfman Disease-Utility of 18F-FDG PET/CT for Initial Evaluation and Follow-up

BACKGROUND

The role of imaging in the management of Rosai-Dorfman disease (RDD), a rare non-Langerhans cell histiocytosis, is not clearly defined. We present an analysis of FDG PET/CT findings obtained for initial disease characterization, follow-up evaluation, and treatment planning for this disease.

METHODS

From an institutional pathology database (2001-2018), we identified RDD patients who underwent FDG PET/CT scans either as part of clinical care or when done as part of clinical trials. For all scans, sites of abnormal FDG uptake were assessed, and SUVmax was measured. Comparison of PET/CT findings was made with anatomic (CT/MRI-based) imaging, where available. Instances of changing treatment based on PET/CT were recorded.

RESULTS

We reviewed 109 FDG PET/CT scans in 27 patients with RDD. Five of 27 patients had only nodal/cutaneous disease, whereas 22 patients had extranodal disease, most commonly in bone (n = 9) and central nervous system (n = 7). PET/CT identified sites of active disease in 24 of 27 patients. All identified bone and extraskeletal lesions, except for a brain lesion in 1 patient, were FDG-avid. In 6 of 20 patients (30%) with available prior CT or MRI, PET/CT demonstrated additional RDD lesions (bones: n = 5, pleura: n = 1) that were not apparent on anatomic imaging; 3 of these lesions were outside the CT field of view, and 3 were not recognized on CT. Overall, 13 of 109 PET/CT scans led to a change in management, affecting 41% (11/27) of patients.

CONCLUSION

FDG PET/CT was valuable in defining disease extent and optimizing treatment strategy in patients with RDD.

An Institutional Review of Tuberculosis Spine Mimics on MR Imaging: Cases of Mistaken Identity

Although MRI has a spectrum of findings which help in the diagnosis of tuberculosis (TB) spine, a broad spectrum of spine pathologies resemble Pott's spine on MRI and are often missed due to inadequate clinical details. As a result, patients are often subject to unnecessary biopsy. A blinded radiologist may misdiagnose such mimic cases as TB. Our aim is to enable the reader to learn the main criteria that differentiate spine TB from other spine etiologies that mimic TB. A retrospective search was done and authors collected only MRI spine reports that showed a differential diagnosis or diagnosis of TB spine from the computer-based data records of the institution over a four-year period. This revealed 306 cases of TB spine out of which 78 cases with an alternate diagnosis that resembled TB spine were included. We describe a single institute review of 78 such cases that resemble and mimic Pott's spine on MRI. The cases being: (n = 15) pyogenic spondylitis, (n = 1) brucellar spondylodiscitis, (n = 12) rheumatoid arthritis, (n = 12) metastases, (n = 8) lymphoma, (n = 5) post-trauma fractures, (n = 10) degenerative disc disease, (n = 2) Baastrup's disease, (n = 9) osteoporotic fracture, (n = 3) spinal neuropathic arthritis, and (n = 1) case of Rosai-Dorfman disease. The clinical and radiological findings of all these cases were correlated with lab findings and histopathology wherever necessary. Appropriate recognition of these entities that resemble and mimic TB spine on MRI is important for optimal patient care. This paper exposes radiologists to a variety of spine pathologies for which biopsy is not indicated, and highlights key imaging findings of these entities to facilitate greater diagnostic accuracy in clinical practice.

Disease Characteristics, Radiologic Patterns, Comorbid Diseases, and Ethnic Differences in 32 Patients With Rosai-Dorfman Disease

OBJECTIVE

Rosai-Dorfman disease (RDD) is a rare and idiopathic nonneoplastic disease of histiocytes that is characterized by lymphadenopathy and extranodal disease. In this study, we documented anatomical preferences, imaging findings, comorbid diseases, and ethnic differences in 32 RDD patients.

METHODS

We conducted a retrospective review of pathologically confirmed cases seen at our institution from 1998 to 2016. These cases were analyzed for (a) anatomical locations, (b) radiologic appearance, (c) comorbid diseases, and (d) differences between ethnic groups.

RESULTS

We found 32 patients with RDD, 18 were women and 14 were men. There were 51 lesions in all patients, 23.5% of which were nodal, involving 11 lymph node regions, and 76.5% were extranodal. Cervical lymph nodes and maxillofacial area were the most common affected nodal and extranodal locations, respectively. Only 4 (12.5%) of 32 patients had pure nodal involvement, whereas 20 (62.5%) of 32 had pure extranodal disease and 8 (25%) of 32 had mixed nodal and extranodal disease.Anatomically, RDD affected multiple organs in our cohort, including the lymphatic system, maxillofacial area (glandular and nonglandular tissues), superficial soft tissue, central nervous system, breast, peritoneum, gastrointestinal tract, and lungs.Radiologically, RDD presentation was variable from an organ to another. However, most lesions were hypermetabolic on 18F-fluorodeoxyglucose positron-emission tomography/computed tomography and isointense on T1-weighted magnetic resonance imaging. Computed tomographic findings were extremely variable between organs.Comorbid diseases were found in 11 patients. Those patients had 17 comorbid diseases; the most common were autoimmune diseases, viral diseases, and cancer.The organ distribution of RDD was slightly different between ethnic groups. The most frequent disease location for African Americans was lymph nodes; for whites, central nervous system and nonglandular maxillofacial (27.3% each); for Asians, lymph nodes, subcutaneous tissue, and nonglandular maxillofacial (25% each); and for Hispanics, lymph nodes and glandular maxillofacial (33.3% each).

CONCLUSIONS

Rosai-Dorfman disease represents a wide-spectrum disease not limited to lymph nodes. Radiologically, RDD has diverse imaging findings. However, most lesions were hypermetabolic on 18F-fluorodeoxyglucose positron-emission tomography/computed tomography and isointense on T1-weighted imaging. Patients with RDD have a high rate of comorbid diseases including autoimmune disease, viral infections, and cancer.

Hypophysitis (Including IgG4 and Immunotherapy)

Hypophysitis is characterized by inflammation of the pituitary gland that can be primary (PH) or secondary (SH) to other diseases or following drug administration. It may also be classified according to anatomical and histopathological criteria, leading to variable degrees of hypopituitarism and/or compressive symptoms to nearby structures. There has recently been an increase in the number of hypophysitis cases, raising the interest on the spectrum of its pathogenesis, clinical, biochemical/endocrinological, and imaging features. However, the use of conventional biomarkers, including currently utilized pituitary autoantibodies, has relatively limited diagnostic accuracy. Lymphocytic hypophysitis (LH) is the commonest cause of PH, whereas IgG4-related hypophysitis is increasingly being recognized. Histiocytosis and granulomatous diseases are the most frequent causes of SH, although infections and lymphoma have also been reported. The increasing use of immune checkpoint inhibitors in oncology is associated with a high incidence of hypophysitis, providing further understanding of its pathogenesis. Hypophysitis can occur silently and be easily missed, potentially leading to substantial morbidity or mortality due to adrenal insufficiency, requiring a high index of clinical suspicion and timely initiation of appropriate treatment. In most cases of LH or drug-induced hypophysitis, active surveillance along with replacement of established hormonal deficiencies is needed. In the presence of compressive and/or evolving symptoms, treatment with glucocorticoids either alone or in combination with other immunosuppressive agents can be used. Surgical decompression is reserved for nonresponsive cases with threatened vital structures. Timely diagnosis and intervention are important to minimize disease-related morbidity and mortality. We aimed to review current concepts and recent developments in the pathogenesis, diagnosis, and management of hypophysitis.

Rosai Dorfman disease of the spine causing lumbosacral radiculopathy: A case report

Rosai Dorfman disease (RDD) also known as sinus histiocytosis with massive lymphadenopathy (SHML) is a rare non-malignant proliferative disorder of unknown etiology. Here we present a case of Rosai Dorfman disease of the spine causing lumbo-sacral radiculopathy. CT and MRI revealed lytic expansile lesion in the left half of L4 vertebra mainly involving posterior aspect involving left pedicle and transverse process. Patient underwent surgery at L3-4 level by left fenestration. Histological examination confirmed the diagnosis of Rosai Dorfman disease. Skeletal involvement is a very rare presentation seen in 2% case with involvement of long bones including tibia, femur, humerus, clavicle and bones of hand. RDD affecting the spine has been rarely reported in literature. A team approach involving the radiologist, spine surgeon, pathologist and oncologist will lead to the early diagnosis and appropriate management of this rare clinical entity.

FDG PET/CT Image for a Rosai-Dorfman Disease With Pituitary and Bone Involvement in a Pediatric Patient

Rosai-Dorfman disease, also known as sinus histiocytosis with massive lymphadenopathy, is a rare nonneoplastic histiocytic disorder that often involves the lymph nodes and occasionally the central nervous system or skeleton. However, the presence of extranodal Rosai-Dorfman lesions without lymphadenopathy is extremely rare. Here we present a case of a pathological confirmed Rosai-Dorfman disease with pituitary and skeletal involvement without lymph nodes involvement.

Isolated Rosai-Dorfman disease with craniocervical junction involvement in the foramen magnum: A case report

RATIONALE

Rosai-Dorfman disease (RDD) is a rare benign histiocytic proliferative disease. RDD with cranio-spinal involvement in the foramen magnum is extremely rare. To the best of our knowledge, only 4 cases of RDD with craniocervical junction involvement have been reported so far. Herein, we present the fifth case of RDD with craniocervical junction.

PATIENT CONCERNS

A 26-year-old female presented with a sudden headache, accompanied by nausea and vomiting several times during the past half-month.

DIAGNOSES

Magnetic resonance imaging (MRI) showed a well-defined, lobulated, homogenous mass in the left foramen magnum. The lesion was isointense on T1-weighted images (T1WI) and hypointense on T2-weighted images (T2WI), and showed homogeneously obvious enhancement following the intravenous administration of gadolinium. It was dural based and extending inferiorly along the spinal dura up to the cervical spinal canal. The brainstem was compressed and deflected to the right side. Initial diagnosis of meningioma with craniocervical junction involvement in the foramen magnum was made according to MRI findings. Final diagnosis of RDD was confirmed by histopathological and immunohistochemical examinations after subtotally surgical resection.

INTERVENTIONS

The bulk of lesion in the foramen magnum was removed surgically with suboccipital craniectomy because of brainstem compression.

OUTCOMES

The patient recovered well and was discharged 17 days after the surgery.

LESSONS

RDD should be considered in patients with dural-based, extra-axial, well-circumscribed, hypo- to isointense on T1WI, hypo- to isointense on T2WI, enhancing intracranial or spinal lesions or both.

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

Histiocytic neoplasms, a rare and heterogeneous group of disorders, primarily include Erdheim-Chester disease, Langerhans cell histiocytosis, and Rosai-Dorfman disease. Due to their diverse clinical manifestations, the greatest challenge posed by these neoplasms is the establishment of a diagnosis, which often leads to a delay in institution of appropriate therapy. Recent insights into their genomic architecture demonstrating mitogen-activated protein kinase/extracellular signal-regulated kinase pathway mutations have now enabled potential treatment with targeted therapies in most patients. This consensus statement represents a joint document from a multidisciplinary group of physicians at Mayo Clinic who specialize in the management of adult histiocytic neoplasms. It consists of evidence- and consensus-based recommendations on when to suspect these neoplasms and what tests to order for the diagnosis and initial evaluation. In addition, it also describes the histopathologic and individual organ manifestations of these neoplasms to help the clinicians in identifying their key features. With uniform guidelines that aid in identifying these neoplasms, we hope to improve the awareness that may lead to their timely and correct diagnosis.

Atypical Case of Rosai-Dorfman Disease of the Lacrimal Gland with Adjacent Bone Erosion

Background/Aims

Rosai-Dorfman disease (RDD) is a rare, self-limited disorder of unknown etiology that affects children and young adults worldwide and typically manifests as chronic, painless cervical lymphadenopathy. Orbital involvement is very rare and may be an isolated extranodal manifestation or associated with concurrent systemic disease. Adjacent bone involvement is most exceptional, and secondary optic neuropathy has never been reported.

Methods

This is a case report with review of the literature.

Results

We present a 32-year-old man who, over a 3-month period, developed worsening vision, headache, and vertical diplopia. On examination, there was decreased vision with dyschromatopsia, proptosis, and hypotropia of the left eye. CT scan of the orbits revealed a soft tissue mass inseparable from the lacrimal gland with adjacent bone erosion. Histopathologic evaluation revealed a diffuse infiltrate of histiocytes, lymphocytes, plasma cells, and neutrophils with peripolesis and emperipolesis (tunneling of lymphocytes and plasma cells in the histiocytes' cytoplasm without destruction), consistent with RDD. Resolution of symptoms as well as of the optic neuropathy was achieved with oral corticosteroids.

Conclusion

RDD is an important diagnosis that must be considered in the differential diagnosis of an orbital mass.

Rosai-Dorfman disease with spinal and multiple intracranial involvement: a case report and literature review

Rosai-Dorfman disease (RDD) is a condition of unknown etiology, and characterized by the proliferation of histiocytes. RDD most commonly affects lymph nodes, and central nervous system (CNS) involvement is rare. Here, we describe the case of a 43-year-old man who presented with an intradural tumour of the thoracic spine. The patient underwent a laminectomy for tumour resection and pathology results diagnosed the tumour as a RDD. Two years later, brain magnetic resonance imaging (MRI) revealed multiple intracranial dural-based lesions. Prednisolone treatment was initiated and led to resolution of the disease. We reviewed the literature to the investigate clinical characteristics, imaging features, diagnosis and treatment protocols pertaining to such cases.

Dural masses: meningiomas and their mimics

Meningiomas are the most common dural tumour. They are regularly being seen as an incidental finding on brain imaging and treated conservatively. However, there are many other dural masses which mimic their appearances, including primary neoplastic processes, metastases, granulomatous diseases and infection. While some of these are rare, others such as metastases and tuberculosis arise relatively frequently in practice. Although not pathognomonic, key features which increase the probability of a lesion being a meningioma include intralesional calcifications, skull hyperostosis, local dural enhancement and increased perfusion. It is important to have an awareness of these entities as well as their main imaging findings, as they have a wide range of prognoses and differing management strategies. This review outlines several of the most important mimics along with their imaging findings on both standard and advanced techniques with key features which may be used to help differentiate them from meningiomas.

Extranodal NK/T-cell lymphoma in adolescents: imaging findings of a consecutive 7-year case series

Objectives

Extranodal NK/T-cell lymphoma is reportedly a rare but emerging type of lymphoma in adolescents. The present study was performed to specify its imaging characteristics.

Methods

Our hospital’s picture archiving and communication systems were searched from January 2009 to December 2016. We identified 13 patients aged <18 years with pathologically confirmed extranodal NK/T-cell lymphoma in the head and neck region. The computed tomography and magnetic resonance images were reviewed to summarize the imaging characteristics of extranodal NK/T-cell lymphoma in adolescents.

Results

The mean age at onset was 15.2 ± 1.46 years (range, 12–17 years) with a male:female ratio of 1.17:1.00. Most of the patients (n = 10) displayed nasal cavity and/or paranasal involvement. The tumor was homogeneous in both computed tomography and magnetic resonance images and showed slight enhancement. No calcification or liquefactive necrosis was observed. Adjacent structures were usually involved.

Conclusion

Suggestive imaging characteristics could acquaint specialists with extranodal NK/T-cell lymphoma in adolescents, facilitating improved early recognition of the diagnosis and helping to improve the patient’s outcome.

Head and Neck Sinus Histiocytosis with Massive Lymphadenopathy Radiology-Pathology Correlation

Sinus histiocytosis with massive lymphadenopathy, or Rosai-Dorfman disease, is a rare, benign type of non-Langerhans cell histiocytosis. The radiological findings are often nonspecific, potentially mimicking malignancies. The diagnosis is ultimately made based on pathology, in which the lymph nodes are characterized by a dilated subcapsular sinus filled with histiocytes that can exhibit emperipolesis. Immunohistochemically, the histiocytes are variably CD68 positive and reliably negative for CD1a. The features of head and neck sinus histiocytosis with massive lymphadenopathy are exemplified in this radiology-pathology correlation sine qua non article.

Multimodality imaging-based evaluation of Rosai-Dorfman disease in the head and neck: A retrospective observational study

Rosai-Dorfman disease (RDD) is an uncommon benign entity characterized histologically by lymphatic sinus dilatation due to histiocyte proliferation. This study was performed to delineate its imaging features, reviewed retrospectively in 12 patients (8 women and 4 men, mean age 58.2 years [range 27-84]) with pathologically confirmed RDD in the head and neck. The location, involvement, and imaging characteristics (CT, magnetic resonance imaging (MRI), and PET/CT) of all lesions were evaluated. Signal intensity on MRI images was compared to gray matter (orbital RDD) and adjacent muscle (sinonasal and cervical RDD). RDD in the head and neck involved multiple sites, primarily the sinonasal cavity (n = 7), neck (n = 3), and orbit (n = 1), with one case of simultaneous involvement of the sinonasal cavity, orbit, and neck. With sinonasal involvement, MRI signal intensity of the involved areas was isointense or slightly hyperintense relative to adjacent muscle on T1WI images and heterogeneous on T2WI images; with lacrimal involvement, it was isointense relative to gray matter on T1- and T2-weighted images; and with neck involvement, it was isointense relative to muscle on T1WI images and relatively hyperintense on T2WI images, with homogenous postcontrast enhancement in all sites of involvement. The lesions on CT were observed as enhancing masses with or without bony destruction. PET/CT showed hypermetabolism in one lesion in the neck. RDD is a rare disorder with multiple sites of involvement in the head and neck. Concomitant cervical lymphadenopathy with extranodal masses assisted by multimodal imaging may be useful in the diagnosis of RDD.

Updates on Immunohistochemical and Molecular Markers in Selected Head and Neck Diagnostic Problems

CONTEXT

- The head and neck regions have complex anatomic structures. They are not exempted from the rare occurrences of highly unusual, diagnostically challenging malignant neoplasms and mimickers.

OBJECTIVE

- To review and update the utility of immunohistochemistry and molecular biomarkers and to pursue diagnostic accuracy on selected rare neoplasms, especially some poorly differentiated malignancies.

DATA SOURCES

- Personal experience and information from the literature.

CONCLUSIONS

- Head and neck tumors include neoplasms originating from heterogeneous tissue. Using the selected clinical cases, this review illustrates a continuous development of emerging molecular-genetic techniques to assist in the interpretation of uncommon, often poorly differentiated, highly malignant neoplasms. The diagnostic results are appropriately transmitted to the oncologists, radiation oncologists, and surgeons to create a coordinated plan of care for patients with these unusual disorders affecting the head and neck.

Systemic Rosai-Dorfman disease with central nervous system involvement

Rosai-Dorfman disease (RDD) is a rare idiopathic and lymphoproliferative disorder. Central nervous system (CNS) involvement is infrequent and typically manifests as an isolated lesion. In this article, we describe an unusual case of RDD with multiple lesions in the CNS, upper respiratory tract and lymph nodes. A literature review revealed 45 cases (including the one described herein) of systemic RDD with CNS involvement documented to date. Among these cases, 29 (64.4%) presented with intracranial lesions, 10 (22.2%) with spinal lesions and 6 (13.3%) with both. While the condition of most patients was stable, only four died from RDD or for other reasons. Prognosis is good for most patients, even those with extensive lesions. Although there are various treatments for RDD, surgery is preferred. Given the rarity of RDD, multicenter international collaborations are advocated in order to study disease pathogenesis and develop effective treatment strategies.

Intraosseous Rosai-Dorfman disease diagnosed by touch imprint cytology evaluation: A case series

Sinus histiocytosis with massive lymphadenopathy, also known as Rosai-Dorfman disease (RDD) is a rare benign disorder that primarily affects the lymph nodes. Localized lymphadenopathy is the most common clinical manifestation of this disorder. However, RDD has been described in several extra-nodal sites including the head and neck region, soft tissue, skin, upper respiratory tract, gastro-intestinal tract and central nervous system (CNS). Involvement of the bone is considered very rare, occurring in less than 10% patients. RDD is one of the histiocytoses and the differential diagnosis includes entities such as Langerhans cell histiocytosis and Erdheim-Chester disease. In the rare intraosseous variant, the clinical and radiologic differential diagnosis is broader and includes neoplasms such as osteosarcoma and Ewing sarcoma. In this report, we describe three cases of extra-nodal, intraosseous RDD where touch imprint cytology played a crucial role in diagnosis. Two of the cases initially presented with involvement of the head and neck region and later developed intraosseous disease; while the third patient presented with primary bone involvement. The diagnosis was established by core biopsy with touch imprints of the bone lesions. The cytologic samples showed numerous histiocytes, often with neutrophils within their cytoplasm (emperipolesis) in addition to lymphocytes and plasma cells. The diagnosis of RDD was confirmed with appropriate immunohistochemical stains. Our account of these three cases of intraosseous Rosai-Dorfman disease highlights the role of cytology in the diagnosis of this rare entity.

Cranio-spinal Rosai Dorfman disease: case series and literature review

Rosai-Dorfman disease (RDD) is a rare condition similar to lymphomas, presenting with cervical lymphadenopathy in young adults. Extra-nodal involvement is relatively common but involvement of the central nervous system (CNS) is rare. Cranial RDD presents with symptoms of raised intracranial pressure, focal or generalised seizures, while spinal RDD presents with pain, peripheral neurological deficits and radiculopathy. In contrast to other similar neoplastic or degenerative conditions affecting the CNS, RDD is a benign, non-infective, granulomatous disorder. Radiologically cranio-spinal RDD often mimics commoner dural-based lesions like meningioma, with only subtle radiological differentiating findings on Magnetic Resonance Imaging (MRI). The histopathology of RDD is diagnostic. Surgical excision is preferred modality of treatment. However, adjuvant therapies like steroids and radiation may help controlling residual or recurrent disease. There are multiple sporadic reports and short case publications in the literature, often focusing on a particular aspect of RDD. In this study, authors aim to present five cases of craniospinal RDD, and comprehensive review of literature and highlight neurological complications of systemic RDD.

Rosai-Dorfman disease of the subdural spine with a long segment lesion: A case report and literature review

Rosai-Dorfman disease (RDD) or sinus histiocytosis with massive lymphadenopathy is a rare benign disorder usually characterized by massive painless cervical lymphadenopathy and systemic manifestations. Extranodal involvement, especially spinal involvement, is extremely rare. We report a 41-year-old man who presented with only intermittent dorsodynia. His condition was diagnosed as non-specific inflammatory disease on the basis of preoperative puncture biopsy results. We performed total surgical resection. Histopathological findings showed distinctive emperipolesis and immunohistochemistry results were positive for cluster of differentiation CD68 and S100 and negative for CD1a. A good prognosis was confirmed at the 3-month follow-up visit. This is the first case of RDD of the subdural spine with such a long segment lesion. There is still no consensus regarding appropriate therapy for this type of RDD and the preoperative diagnosis remains challenging. The unusual presentation of our case serves as a reference when diagnosing and treating RDD.

Unusual presentation of Rosai-Dorfman disease in a 14-month-old Italian child: a case report and review of the literature

Background

Rosai-Dorfman disease (RDD) is a rare form of histiocytosis characterized by histiocyte proliferation within lymph nodes and extranodal tissue. Here we report an unusual presentation of RDD in an Italian toddler. Moreover, we reviewed the pediatric case reports published between 2004 and 2014, focusing in particular on medical therapy.

Case presentation

We report the case of a 14-month-old child who developed a progressive swelling of the right parotid, associated with systemic symptoms and abnormal blood tests. During diagnostic work-up, cervical, intraparotid, and unilateral hilar lymphadenopathies were found. Histopathological and immunohistochemistry studies of a cervical lymph node biopsy established the diagnosis of RDD, with positive PCR for Epstein - Barr virus on the biopsy specimen. Oral steroid therapy was started with progressive reduction in size of all lesions, resolution of systemic symptoms, and normalization of blood tests.

Conclusion

RDD is generally considered a benign and self-limiting form of histiocytosis, usually associated with favorable prognosis. However, complications are not infrequent and fatal cases were reported even in children. Efforts should be made to establish the best therapeutic strategy for this disease, as no well-defined guidelines exist. Finally, RDD should be included in differential diagnosis of lymphadenopathy and parotid swelling even in very young children.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-016-0595-9) contains supplementary material, which is available to authorized users.

Redefining the Prevalence of Dural Involvement in Rosai-Dorfman Disease of the Central Nervous System

BACKGROUND

Sinus histiocytosis with massive lymphadenopathy, also known as Rosai-Dorfman disease, is a rare condition, classically characterized by painless, massive cervical lymphadenopathy. Histologically, the pathognomonic findings include a dense, mixed inflammatory infiltrate with areas of emperipolesis. Albeit infrequent, when Rosai-Dorfman disease affects the central nervous system, it typically manifests as an isolated dural lesion, often mimicking a meningioma. A purely intraparenchymal manifestation of Rosai-Dorfman disease of the brain and spine with absent dural involvement is exceedingly rare.

CASE DESCRIPTION

In this report, we describe a 59-year-old woman who underwent surgical excision of an intraparenchymal cerebellar lesion. Histologic analysis of the resected specimen diagnosed isolated Rosai-Dorfman disease with absent systemic involvement. We also provide an updated review of the literature of nondural-based Rosai-Dorfman disease in the central nervous system.

CONCLUSIONS

With the recent increase of such reported cases, it becomes imperative that Rosai-Dorfman be considered more than as a dural lesion that may mimic meningioma. Diagnostic and therapeutic challenges surrounding this disease entity are also discussed.

Central Nervous System and Head and Neck Histiocytoses: A Comprehensive Review on the Spectrum of Imaging Findings

The histiocytoses are a rare group of varied but related disorders characterized by abnormal tissue proliferation of macrophages and dendritic cells within tissues. The purpose of this article was to review the imaging findings in patients presenting with CNS and with head and neck manifestations of these disorders. Histiocytoses include but are not limited to Rosai-Dorfman disease, Erdheim Chester disease, Langerhans cell histiocytosis, histiocytic sarcoma, and juvenile xanthogranuloma. A review of the literature was performed to determine the sites of disease involvement. This article includes the demographics, histopathologic criteria for diagnosis, and imaging features of these histiocytoses, and describes the manifestations in locations known to harbor disease: intraaxial and extra-axial intracranial regions, the calvaria, skull base, hypothalamopituitary axis, orbits, paranasal sinuses, spine, and the head and neck region. Histiocytoses have variable imaging appearances in the CNS and in the head and neck region, and radiologists should be aware of the spectrum of findings to avoid mistaking them for other disease processes.

Learning Objective

To understand the general pathophysiology, clinical presentation, and typical imaging characteristics of the most common histiocytoses; comprehend the morphologic and immunohistochemical characteristics of these histiocytoses and the hallmark findings on pathology; and be able to differentiate between these disorders based on their most common presentations.

Rosai-Dorfman Disease Isolated to the Thoracic Epidural Spine

Rosai-Dorfman disease is a rare benign histiocytic disease that infrequently presents in the spine. We report a case of Rosai-Dorfman disease isolated to the epidural thoracic spine in a 26-year-old male. To our knowledge, this is the 15th reported case of isolated spinal disease and only the fourth case of isolated thoracic epidural disease. Given its rarity as well as non-specific symptoms and imaging findings, Rosai-Dorfman disease is often not considered and misdiagnosed on imaging studies. To help improve awareness of Rosai-Dorfman spinal disease, we review the literature and discuss the epidemiology, clinical presentation, imaging features, and treatment considerations for this condition.

More than just Langerhans cell histiocytosis: a radiologic review of histiocytic disorders

Although Langerhans cell histiocytosis (LCH) is a familiar entity to most radiologists and to pediatric radiologists in particular, it is but one of a group of disorders caused by the overproduction of histiocytes, a subtype of white blood cells. Other less familiar diseases in this category are Erdheim-Chester disease (ECD), juvenile xanthogranuloma (JXG), Rosai-Dorfman disease (RDD), and hemophagocytic lymphohistiocytosis (HLH). This review describes the classification system, clinical manifestations, and pathophysiology of each disease, with particular attention to differential radiographic findings, including typical locations of involvement and varying appearances at radiography, computed tomography, magnetic resonance imaging, ultrasonography, and nuclear medicine imaging. Although LCH has a wide variety of manifestations and appearances, classic imaging findings include vertebra plana, skull lesions with a beveled edge, the "floating tooth" sign, bizarre lung cysts, and an absent posterior pituitary bright spot with infundibular thickening. The classic imaging findings of ECD are a perirenal rind of soft tissue and patchy long bone osteosclerosis. RDD has more nonspecific imaging findings, including lymphadenopathy (most commonly cervical) and intracranial lesions. Imaging findings in HLH are broad, with the most common abnormalities being hepatosplenomegaly, cerebral volume loss, and periventricular white matter abnormalities. JXG can manifest at imaging, but radiology does not play a major role in diagnosis. Familiarity with these disorders and their associated imaging findings facilitates correct and timely diagnosis. Imaging also features prominently in the assessment of treatment response.