An unusual presentation of unifocal Rosai-Dorfman disease and surgical treatment

Rosai-Dorfman disease (RDD) is a rare histiocytic disorder with an unclear aetiology, and commonly presents with painless, bilateral cervical lymphadenopathy. Extranodal presentation in the absence of nodal involvement has been reported to have a predilection for the head and neck with less than 20 cases involving the jaw bones and sinuses. We present an interesting case of unifocal RDD of the infratemporal space in the absence of nodal involvement in a 61-year-old female treated with surgical excision and adjuvant radiation therapy.

A rare presentation of Rosai-Dorfman disease involving the central nervous system

A 29-year-old gentleman diagnosed with Rosai-Dorfman disease (RDD) on corneal biopsy, 2 years ago, presented with fluctuating left-sided numbness, intermittent slurred speech, and urinary incontinence, progressively worsening over the past three months.

Rosai-Dorfman disease manifesting as a solitary mass with fat in the thymus a case report

BACKGROUND

Sinus histiocytosis with massive lymphadenopathy, also known as Rosai-Dorfman disease, is a rare, self-limiting disease that predominantly affects children and young adults. Moreover, the disease is characterized by painless bilateral cervical lymphadenopathy in 95% of the patients. However, few reports are available on the Rosai-Dorfman disease of the thymus.

CASE PRESENTATION

We report a rare case of thymic Rosai-Dorfman disease detected using computed tomography. During a medical examination, a 50-year-old man underwent a chest computed tomography scan, which revealed an anterior mediastinal single mass with fat in the thymus. A thymectomy was performed to completely remove the tumor using a thoracoscopic technique due to a clinical suspicion of thymoma. Furthermore, Rosai-Dorfman disease was confirmed using histological and immunohistochemical analyses.

CONCLUSIONS

To the best of our knowledge, this is the sixth case of thymus-affecting solitary Rosai-Dorfman disease with histological and immunohistochemical evidence. Fat in the thymus, as was present in this case, has never been described in Rosai-Dorfman disease previously. Our results highlight the challenge of diagnosing this uncommon tumor before surgery, and more cases need to be reported to help with the preoperative diagnosis of such a rare tumor.

Diagnostic consideration of lipoma-like lesion: A case report of primary cutaneous Rosai-Dorfman disease

INTRODUCTION AND IMPORTANCE

Rosai-Dorfman disease (RDD) is a rare disorder characterized by benign histiocytic proliferation. The purely cutaneous variant of Rosai-Dorfman disease is exceptionally uncommon. This abstract centers on an extraordinary case-an instance of primary cutaneous Rosai-Dorfman disease (PCRDD), a rare cutaneous variant within an already infrequent disorder. Successfully managed through surgical intervention, this unique case underscores the pressing need for refined diagnostic and therapeutic strategies.

CASE REPORT

We present a noteworthy case of primary cutaneous Rosai-Dorfman disease (PCRDD) in a north African female, deviating from the typical age of onset. The patient exhibited a rare cutaneous variant, emphasizing the need for heightened awareness in diverse demographics. Histological analysis revealed characteristic emperipolesis and immunohistochemical features consistent with RDD.

CLINICAL DISCUSSION

PCRDD, although uncommon within the Rosai-Dorfman Disease spectrum, manifests with a later onset and distinctive demographic characteristics. Surgical excision emerges as a viable therapeutic option for managing symptomatic lesions, as demonstrated in our case. The infrequency of PCRDD underscores the importance of tailored diagnostic and therapeutic strategies. Individualized approaches become pivotal in addressing the complexities associated with PCRDD, ensuring careful consideration of its intricacies in the broader context of Rosai-Dorfman disease.

CONCLUSION

This case underscores the complexity of RDD, especially in rare cutaneous presentations. Surgical excision, with its reported efficacy, stands as a crucial intervention, offering both symptomatic relief and potential cure, showcasing the significance of individualized care in managing this rare disorder. Continued research remains imperative for advancing RDD understanding and refining clinical approaches.

Successful Treatment of Rosai-Dorfman Disease with Cutaneous Involvement and Arthritis with Methotrexate and Infliximab

Rosai-Dorfman disease (RDD) is a rare histiocytic proliferative disorder characterized by lymphadenopathy and extra-nodal manifestations. Some patients with RDD require systemic treatment, but there is no consensus on the treatment strategy owing to its extreme rarity. Overexpression of tumor necrosis factor α (TNF-α) has been reported in lesions of patients with RDD and is thought to be involved in its pathogenesis. We herein report the first case of RDD with cutaneous involvement and arthritis that was successfully treated with methotrexate and infliximab. This case highlights the potential efficacy of anti-TNF-α therapy for RDD, offering a novel treatment option for this rare condition.

Uncommon presentation of Rosai-Dorfman disease: Nasal and nasopharyngeal involvement: A case report and discussion

This study presents a rare case of Rosai-Dorfman disease (RDD) with nasal and nasopharyngeal involvement, illustrating the complexities in diagnosing this enigmatic histiocytic disorder. RDD, characterized by massive, painless cervical lymphadenopathy, poses diagnostic challenges due to its diverse clinical presentations. In this case, a 38-year-old woman presented with a year-long history of neck swellings, nasal congestion, headaches, and sinusitis-like symptoms. Radiological imaging and histopathological examination revealed RDD involvement in the nasopharynx and paranasal sinuses. RDD diagnosis was confirmed through immunohistochemistry. The patient's unique symptoms emphasize the importance of considering RDD in the differential diagnosis of sinonasal masses with recurrent or unusual complaints. This case underscores the need for increased awareness, multidisciplinary management, and further research to enhance understanding and treatment of RDD, especially in extranodal presentations.

A Case of Isolated Central Nervous System Rosai-Dorfman Disease

Rosai-Dorfman disease (RDD) is a benign histiocytosis with unknown etiology. It generally occurs in cervical lymph nodes. Isolated central nervous system (CNS) RDD is very rare in the literature. We reported a case of no systemic involvement Rosai-Dorfmann which is rarely seen and shows CNS involvement by mimicking meningioma. A 32-year-old man presented with diplopia and a headache he has been experiencing for the past two years. His neurological examination showed left facial paresthesia, consistent with trigeminal nerve trace. Tendon reflexes were increased at the right side and the right plantar reflex was extensor. Brain magnetic resonance imaging demonstrated irregularly shaped, tumor-like lesions in the bilateral cerebellopontin area that were compressing pons. Rosai-Dorfman disease can be differentiated from IgG4 related disease (IgG4-RD) by its characteristic features such as plasma cell density and emperipolesis seen in its histopathology. Rosai-Dorfman disease can be confused with other diseases radiologically and histopathologically, especially the IgG4-RD, so be careful about differential diagnosis.

[Pediatric orbital Rosai-Dorfman disease: An unusual case]

INTRODUCTION

Rosai-Dorfman disease (RDD) is a sinus histiocytosis with massive lymphadenopathy. This rare condition is a benign disease of unknown etiology. Bilateral orbital localization of RDD is rare.

OBSERVATION

The authors report the case of a 6-year-old child who presented with bilateral orbital-palpebral masses associated with chronic cervical lymphadenopathy. There were no laboratory signs of inflammation. Serological and tuberculosis screening tests were negative. Histopathological examination of a lymph node biopsy established a diagnosis of Rosai-Dorfman disease. The patient underwent surgical excision of the orbital lesions followed by long-term corticosteroid therapy. A favorable course was observed, with no sign of recurrence after one year of follow-up.

CONCLUSION

Rosai-Dorfman disease is very rare in its bilateral orbital presentation. Histopathological diagnosis remains challenging. In Africa, the presence of chronic oculo-palpebral tumor associated with or without cervical lymphadenopathy must raise the suspicion of Rosai-Dorfman disease after ruling out tuberculosis and lymphoma.

Treatment of cutaneous Rosai-Dorfman disease with ALA-PDT combined with low-dose oral corticosteroids: A case report

Cutaneous Rosai-Dorfman Disease (CRDD), a rare form of Rosai-Dorfman Disease (RDD), lacks established treatment guidelines. In this case report, we detailed a successful case of CRDD management in a 50-year-old woman with facial lesions. Our treatment included 5-aminolevulinic acid photodynamic therapy (ALA-PDT) and low-dose oral corticosteroids. Remarkable improvement was evident after six ALA-PDT courses, and a one-year follow-up confirmed sustained remission. This case highlights the potential of combining ALA-PDT with low-dose corticosteroids as a promising therapeutic strategy for CRDD. Further research is necessary to fully elucidate its mechanisms and effectiveness.

Rosai-Dorfman disease of the cauda equina: illustrative case

BACKGROUND

Rosai-Dorfman disease (RDD) is a rare, nonmalignant histiocytosis. It typically occurs in lymph nodes, skin, and soft tissues, but numerous reports of central nervous system involvement exist in the literature. The peripheral nervous system has rarely been involved. In this study, the authors present a case of RDD isolated to the cauda equina. The presentation, management, surgical technique, and adjunctive treatment strategy are described.

OBSERVATIONS

A 31-year-old female presented with 6 months of progressive left lower-extremity numbness involving the lateral aspect of the foot and weakness of the left toes. Magnetic resonance imaging of the lumbar spine demonstrated a homogeneously enhancing intradural lesion involving the cauda equina at the L2-3 levels. Histopathology after resection revealed a histiocytic infiltrate, positive for CD68 and S100, and emperipolesis consistent with RDD. No adjuvant therapy was administered, and the patient had full remission at the 1-year follow-up. Only five other cases of intradural RDD lesions of the cauda equina have been reported in the literature.

LESSONS

RDD of the cauda equina is an especially rare and challenging diagnosis that can mimic other dura-based lesions, such as meningiomas. A definitive diagnosis of RDD relies on pathognomonic histopathological and immunohistochemical findings.

Synchronous occurrence of primary cutaneous B-cell lymphoma and cutaneous Rosai-Dorfman disease in distinct lesions: A unique association

Rosai-Dorfman disease, also known as sinus histiocytosis with massive lymphadenopathy (SHML), is a rare subtype of reactive histiocytosis which is seldom associated with Hodgkin's and non-Hodgkin's lymphomas. To date, the coexistence in the same patient of extra nodal SHML and primary cutaneous B-cell lymphoma (PCBCL) has been reported in the literature, as metachronous diagnosis in the anatomical area of the original PCBCL or synchronous occurrence in the same lesions. However, no data have been published as for synchronous occurrence of the two pathological entities in distinct anatomical sites. Herein, we report the first ever described synchronous occurrence of PCBCL and SHML, detected in distinct lesions, affecting the same patient. The complete resolution of the patient's PCBCL after rituximab treatment and the concomitant regression of SHML suggest that this clinically benign reactive histiocytic proliferation, potentially triggered by the lymphoma microenvironment itself, may take place not only in the site of the PCBCL lesion, but also in other distant areas not directly affected by the primary cutaneous lymphoma.

Cerebral manifestation and diagnostic dilemma of Rosai-Dorfman disease

Rosai-Dorfman disease (RDD) is a rare, S100-positive histiocytic proliferation, that can cause both nodal and extranodal illness. We present a case of a 53-year-old male patient. Magnetic resonance imaging described a plaque-like meningeal lesion, and the preoperative diagnosis was meningioma. Histologically, dense infiltration of lymphocytes, plasma cells, and histiocytes was seen, furthermore, the presence of emperipolesis in the sample was pronounced. In the histiocytes nuclear and cytoplasmic positivity with S100 protein, and nuclear positivity with Cyclin D1 was observed. The case was concluded as RDD. Morphological appearance of intracranial RDD with imaging procedures can present a differential diagnostic challenge. The correct diagnosis is based on the presence of histiocytes with emperipolesis, and properly defined immunohistochemical characteristics.

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.

Facial Cutaneous Rosai-Dorfman Disease: Dermoscopic Findings with Successful Surgical Treatment

Rosai-Dorfman disease (RDD) is a rare non-Langerhans cell histiocytosis characterized by an accumulation of activated histiocytes within the affected tissues. It is a heterogeneous disease that includes the classical (nodal) and extra-nodal variants. The cutaneous form of the disease without the characteristic lymphadenopathy is rare and is often misdiagnosed as other dermatologic diseases. Misdiagnosis as lymphoproliferative and infectious diseases such as lymphoma and tuberculosis have been reported in the literature. Herein, we report a case of facial cutaneous RDD with successful surgical treatment. In addition, we provide dermoscopic findings and literature review as dermoscopy can be a useful adjuvant tool in the diagnosis of cutaneous RDD.

The changing landscape of pediatric histiocytoses: Birth, life, and transdifferentiation of pediatric histiocytes

Histiocytic neoplasms in the children are very rare, and histiocytoses can occur in the perinatal period. The presumed origins and presentation of specific histiocytoses in the pediatric age group are described. Common and newly described histiocytoses are presented including Langerhans cell histiocytosis, Rosai-Dorfman disease, histiocytic sarcoma, ALK positive histiocytosis, and hemophagocytic lymphohistiocytosis. Molecular findings common to pediatric histiocytoses are also discussed.

Rosai-Dorfman disease of the breast: a clinicoradiologic and pathologic study

Rosai-Dorfman disease (RDD) is an uncommon histiocytic disorder typically involving lymph nodes and less frequently extranodal tissues. RDD involving the breast is rare and may clinically and radiologically mimic neoplastic and non-neoplastic disorders. We report seven patients with breast RDD, describe their clinicoradiologic and pathologic features, and discuss the differential diagnosis. Patients, ranging from 15 to 74 years of age, presented with unilateral and unifocal (5/7) or bilateral and multifocal (2/7) masses. RDD was either confined to the breast (6/7) or concurrently involved a lymph node (1/7). Masses ranged from 8 to 31 mm, categorized as Breast Imaging-Reporting and Data System (BI-RADS) 4 (6/7) or 5 (1/7). All cases showed similar morphology with many large histiocytes displaying emperipolesis with associated fibrosis and dense lymphoplasmacytic infiltrate. The abnormal histiocytes co-expressed CD68/CD163, S100, OCT2, and Cyclin D1 (7/7), and were negative for CK AE1/AE3 (7/7), CD1a (7/7), and BRAF V600E (6/6). Flow cytometry (n = 3), kappa/lambda in situ hybridization (n = 5), and IgG4/IgG immunohistochemistry (n = 1) did not reveal lymphoma or IgG4-related disease. No mycobacterial or fungal organisms were identified on acid-fast bacillus (AFB) and Grocott methenamine silver (GMS) stains (n = 5). Three patients underwent complete excision and none recurred or progressed to systemic disease during follow-up (88-151 months). In summary, breast RDD should be included in the differential diagnosis of a mass-forming breast lesion. Histopathology with ancillary studies and clinicoradiologic correlation is essential for accurate diagnosis and optimal clinical management. Patients with RDD of the breast have an excellent prognosis after complete excision.

Primary Bilateral Intraosseous Rosai-Dorfman Disease

Rosai-Dorfman disease (RDD) is a rare histiocytic proliferative disease of unknown etiology. Typically presenting with cervical adenopathy and constitutional symptoms, RDD involves bone in less than 10% of cases-and rarely presents as a primary intraosseous lesion. In this report, we describe the presentation of primary, bilateral intraosseous RDD, the first known case in the literature. Asymmetrically involving the lateral femoral condyles of a 59-year-old male, the lesion was discovered incidentally during evaluation and workup for giant cell tumor of bone involving the left tibia. Confirmation of the diagnosis required multiple biopsies and extensive evaluation-reflecting the diagnostic challenge associated with this case. We discuss the clinical, radiological, and pathological findings that allowed us to establish the diagnosis-as well as key differential diagnostic considerations and clinical outcome to date.

Malignus emlőtumor? Gyulladásos emlőelváltozás? Ritka benignus kórkép?

Case-report

Rosai-Dorfman disease, also known as sinus histiocytosis with massive lymphadenopathy is a rare, benign non-Langerhans cell histiocytosis, that typically involves the lymph nodes, but may also involve extranodal sites. We present a 58- years- old female patient who complained of a palpable mass in her left breast surrounded by 15-20 livid cutaneous lesions, resembling malignant breast cancer with cutaneous metastasis. Despite of core biopsy of the tumor and excisional biopsy one of the lesions, correct diagnosis of RDD was achieved only by complete pathological examination of the whole lesion after surgical excision.

Conclusion

Rosai-Dorfman disease confined to the breast is extremely rare, that clinically may mimic breast cancer.

Intracranial Rosai‑Dorfman disease complicated by mucosa‑associated lymphoid tissue: A case report

Intracranial Rosai-Dorfman disease (RDD) is a rare, self-limiting histiocytic disease of unknown etiology. Extranodal marginal zone lymphoma of the mucosa-associated lymphoid tissue (MALT lymphoma) is also rare and intracranial RDD complicated by MALT lymphoma is even rarer. The present study reports a case of a 55-year-old female who was admitted to The Second Affiliated Hospital of Jiaxing University (Jiaxing, China) with headache for half a month and ptosis of the right eyelid for 4 days. Computerised tomography and magnetic resonance imaging revealed a right parasellar tumor and, subsequently, subtotal resection of the tumor was performed. Postoperative pathology revealed intracranial RDD complicated by MALT lymphoma. The patient received chemotherapy after surgery and achieved good therapeutic effects. After 12 months of follow-up, the residual tumor disappeared and the ptosis prominently improved. To the to the best of the authors' knowledge, the present case is the first reported case of an adult intracranial RDD complicated by MALT lymphoma.

Rosai-Dorfman-Destombes Disease in the Pediatric Head and Neck

BACKGROUND

Rosai-Dorfman-Destombes disease (RDD), or sinus histiocytosis with massive lymphadenopathy, is a rare form of non-Langerhans cells histiocytosis. It has a wide-ranging variability in presentation since first described in 1969 but much of its characteristics in children remain unknown.

METHODS

A retrospective chart review of children diagnosed with RDD at a tertiary care children's hospital was conducted from 2000 to 2021.

RESULTS

Twelve RDD patients were identified, with an average age of 7 years (SD 4.3). Males comprised 58% of the cohort, and African American ethnicity was most common (42%). Nodal RDD was found in 7 patients (58%). Nine patients (75%) presented RDD within the head and neck, 6 of whom had nodal RDD. The most common presentation was cervical lymphadenopathy, which most often involved levels V (67%), II (56%), III (44%), and I (11%), in order of frequency. Recurrence and persistence of disease after initial treatment was common, with 5 (42%) being disease free at the time of the last follow up. Fifty-eight percent (7/12) developed recurrence or had persistent disease and 4 required adjuvant systemic treatment with corticosteroids and/or chemotherapy. One patient succumbed after developing treatment related acute myelodysplastic leukemia (t-AML) from chemotherapy used to treat recurrent RDD.

CONCLUSION

Pediatric RDD presents at a young age and most commonly involving cervical lymphadenopathy. Ongoing surveillance in the setting of persistence or recurrence without clearly defined prognostic risk factors is important.

Characterizing Rosai-Dorfman disease with [18F]FDG PET/CT: a retrospective analysis of a single-center study

OBJECTIVES

Rosai-Dorfman disease (RDD) is a rare non-Langerhans cell histiocytic proliferative disorder. We performed a retrospective study to characterize the clinical and [18F]FDG PET/CT features of RDD.

METHODS

We retrospectively recruited 38 RDD patients with [18F]FDG PET/CT scan in our center. [18F]FDG PET/CT features were assessed, and clinical and follow-up data were recorded.

RESULTS

In the recruited patients, 20/38 (52.6%) patients had single-system disease, while others (18/38, 47.4%) had disease affecting multiple system. RDD most commonly involved the upper respiratory tract (47.4%), followed by cutaneous/subcutaneous lesion (39.5%), lymph node (36.8%), bone (31.6%), central nervous system (28.9%), and cardiovascular system (13.2%) in the recruited patients. In PET/CT, the RDD lesions were FDG-avid, and the SUVmax of the hottest lesion in an individual patient was positively correlated with C-reactive protein levels (r = 0.418, p = 0.014), and negatively correlated with hemoglobin levels (r =  -0.359, p = 0.036). The overall response rate of the first-line treatment was 80.8% in newly diagnosed RDD patients, and for patients with relapsed/progressive RDD, the overall response rate was 72.7%.

CONCLUSION

[18F]FDG PET/CT could be a useful tool for evaluating RDD.

KEY POINTS

• About half of the patients with Rosai-Dorfman disease had single-system disease, while others had disease affecting multiple system. Rosai-Dorfman disease most commonly involved the upper respiratory tract, followed by cutaneous/subcutaneous lesion, lymph node, bone, central nervous system, and cardiovascular system. • In [18F]FDG PET/CT, Rosai-Dorfman disease was usually hypermetabolic, and the SUVmax of the hottest lesion in an individual patient was positively correlated with C-reactive protein levels. • Rosai-Dorfman disease usually has a high overall response rate after treatment.

Illustrative case

BACKGROUND

Rosai-Dorfman disease (RDD) is a rare non-Langerhans histiocytic disorder with less than 5% central nervous system involvement and is often mistaken for meningioma given the similarity in imaging features. The authors present the unique case of a 44-year-old female who presented with ongoing visual impairment.

OBSERVATIONS

A purely suprasellar mass was noted on magnetic resonance imaging and was initially diagnosed as craniopharyngioma. Unexpectedly, the pathology report revealed RDD.

LESSONS

To date, only six cases of sellar RDD have been reported, and our case is the first reported with a purely suprasellar presentation. No standard treatment has been established for RDD, and next-generation sequencing may be a promising therapeutic option.

Rosai-Dorfman Disease of the Rectum: Newly Identified Genetic Point Mutations and Robotic Resection

Rosai-Dorfman disease (RDD) is a rare disease characterized by histiocytic proliferation which typically presents as massive, painless, cervical lymphadenopathy in children or young adults. GI involvement is exceedingly rare with only 20 documented cases to date. Of those 20 cases, only 3 cases have involved the rectum. Here, we present 2 cases of rectal RDD with attention paid to the diagnostic and technical challenges presented by this disease. When presenting as a perirectal mass, RDD can be mistaken for other lesions to include malignancy, leading to surgical removal. We present a video of a robotic low-anterior resection with intracorporeal anastomosis in order to remove a pelvic mass involving the rectum, initially considered to be a stromal tumor. In addition, we describe a copy number variation in AKT and 3 point mutations detected by next generation sequencing, which had not been previously reported in association with this disease.

Neurological Manifestations of Histiocytic Disorders

PURPOSE OF REVIEW

Histiocytic disorders, including Erdheim-Chester disease (ECD), Langerhans cell histiocytosis (LCH), and Rosai-Dorfman disease (RDD), are rare neoplasms that may present with a spectrum of neurologic involvement. Diagnostic delay is common due to heterogeneity in presentation and challenging pathology.

RECENT FINDINGS

Recent advances in the treatment of these diseases targeted towards mutations in the MAP kinase pathway have led to an improved prognosis in these patients with neurologic involvement. It is critical for clinicians to have a high index of suspicion to allow for early targeted treatment and optimize neurologic outcomes. A systematic approach to diagnosis is presented in this article to allow for accurate diagnosis of these rare diseases.

Testicular Rosai-Dorfman disease clonally related to CMML - Case report and literature review

BACKGROUND

Rosai-Dorfman disease (RDD), a rare form of non-Langerhans cell histiocytosis with heterogenous clinical features, arises from precursor cells that give rise to cells of the histiocytic and monocytic lineages. An association with hematological neoplasms has been reported. Testicular RDD is rarely described, with only 9 reported cases in the literature. Genetic data to assess clonal relationships between RDD and other hematological neoplasms remain scarce. We describe an instance of testicular RDD against a background of chronic myelomonocytic leukemia (CMML), with genetic studies in both neoplasms.

CASE PRESENTATION

A 72-year-old patient with a history of CMML sought evaluation of growing bilateral testicular nodules. Solitary testicular lymphoma was suspected; orchidectomy was performed. The diagnosis of testicular RDD was established morphologically and confirmed immunohistochemically. Molecular analysis of testicular lesions and of archived patient bone marrow revealed the KRAS variant c 0.35 G>A / p.G12D in both, suggesting a clonal relationship.

CONCLUSION

These observations support classifying RDD as a neoplasm that can be clonally related to myeloid neoplasms.

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.

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.

Recurrent central nervous system Rosai-Dorfman disease with KRAS mutation: a case report

BACKGROUND

Rosai-Dorfman disease (RDD) is a rare, non-Langerhans cell histiocytosis of unknown etiology. we report a very rare case of recurrent central nervous system RDD with KRAS gene mutation and review the literature to improve our understanding of this disease.

CASE PRESENTATION

A 19-year-old male patient was admitted to our hospital for headache. Cranial magnetic resonance imaging revealed a mass of abnormal signal shadows in the prepontine cistern. The mass was surgically removed and the patient was consequently diagnosed with intracranial Rosai-Dorfman disease. Seven months later, pathological examination confirmed that the RDD had recurred. Next-generation sequencing found KRAS mutation in exon 4 (C.351A > C. P. K117n).

CONCLUSION

RDD of the CNS has no distinct clinical manifestations and imaging characteristics, and the final diagnosis should be based on the results of the pathological examination. Although RDD is not currently classified as a neoplastic disorder, some evidence of clonality has changed our understanding of it. Follow up examinations over a long period are necessary to determine the efficacy of treatment.

OCT2 expression in histiocytoses

Diagnosis of histiocytosis can be difficult and one of the biggest challenges is to distinguish between reactive and neoplastic histiocytes on histology alone. Recently, OCT2 nuclear expression was reported in Rosai-Dorfman disease (RDD). Our purpose was to expand the testing of OCT2 on a broader variety of sporadic or H syndrome-related histiocytoses. Cases of histiocytoses were retrieved from the files of Ambroise Paré Pathology Department. All slides and molecular analyses were reviewed, and staining was completed with immunohistochemistry for OCT2. A total of 156 samples from different localizations were tested. Among sporadic cases, 52 patients had RDD, and 10 patients had mixed histiocytosis combining RDD with Erdheim Chester disease (ECD, n = 8), Langerhans cell histiocytosis (LCH, n = 2) or juvenile xanthogranuloma (JXG, n = 1). All these patients were positive for OCT2 in RDD characteristic histiocytes. Twenty-three patients had ECD and all but two (91% - 21/23) were negative for OCT2. By contrast, OCT2 was positive in 11/27 (41%) LCH and 6/16 (38%) JXG. Among the 10 samples of H syndrome-associated histiocytosis, 3 had typical RDD histology, 6 had unclassified histiocytosis, and one had mixed RDD-LCH; all were positive for OCT2. On 16 samples of granulomatous lymphadenitis, OCT2 was negative in epithelioid histiocytes. Our study shows that OCT2 has a sensitivity of 100% for RDD cases and mixed histiocytoses with an RDD component. It is negative in 92% of ECD but expressed in at least 38% of LCH, JXG, and C group histiocytoses. Finally, OCT2 is positive in all H syndrome-related histiocytoses, independent of their histology.

A Rare Case of Rosai-Dorfman Disease Affecting the Brachial Plexus: A Case Report

Sinus histiocytosis with massive lymphadenopathy or Rosai-Dorfman disease is a rare but well-established entity, commonly affecting the lymph nodes of the head and neck. Extranodal presentation, affecting the central nervous system, eye orbit, kidneys, testis, bones, upper respiratory tract, lungs, thyroid, small intestine, and peritoneum, has been reported. We present a case of a rare presentation of Rosai-Dorfman disease affecting the brachial plexus.

Case report: Rosai-Dorfman disease with rare extranodal lesions in the pelvis, heart, liver and skin

Rosai-Dorfman disease (RDD), a rare form of non-Langerhans cell histiocytosis, can involve systemic extranodal lesions. Skin lesions are the most common, whereas intrapelvic, cardiac, and hepatic lesions are infrequent. The present study describes a 74-year-old woman with multiple extranodal lesions in the pelvis, heart, liver, and skin that were successfully treated with glucocorticoid therapy. She had experienced fever and persistent inflammation without cervical lymphadenopathy for several months and ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) showed abnormal FDG uptake in the left cheek; cervical, axillary, inguinal lymph nodes; periatrium; and pelvis. She was diagnosed with RDD based on skin and pelvic biopsies. Although this was an atypical case without bilateral cervical lymphadenopathy, the FDG-PET detection of inflammatory lesions led to selection of suitable biopsy sites, and pathological examination led to a correct diagnosis. Findings in this patient indicate that RDD can present with an atypical distribution of infrequent extranodal lesions, with attention required to prevent a delayed diagnosis.

A report of Rosai-Dorfman disease with systemic multiple lymphadenopathy and high IgG4 plasma cell infiltration

The Rosai-Dorfman disease (RDD) is a kind of sinus histiocytosis with massive lymphadenopathy and is remarkably rare. RDD is characterized by large histiocytes with emperipolesis. However, the cause of RDD is unknown, and most cases are relieved spontaneously. In rare cases, patients may have onset and remission of lymph nodes and extranodal involvement. This report showed an RDD case in a 67-year-old male patient with systemic superficial lymphadenopathy and high IgG4 plasma cell infiltration. We showed that a possible RDD diagnosis should be kept in mind when encountering a systemic multiple lymphadenopathy and high IgG4 plasma cell infiltration. Also, an overlap between RDD and IgG4-related disease might be present, which might help in clinical recognition of RDD.

Bifocal Intracanial Rosai-Dorfman Disease Mimicking Lymphoplasmacyte-Rich Meningioma: Diagnostic Pitfalls About a Case Report

Rosai-Dorfman disease (RDD) is a clonal histiocytic proliferation characterized by large S100 positive histiocytes with variable emperipolesis. Extranodal locations were confirmed with the central nervous system or the meninges involvement in less than 5% of cases, which is marked as a significant differential diagnosis of meningiomas in radiological and intra-operative pathological examination. Histopathology and immunohistochemistry are the keys to definitive diagnosis. We present a case of bifocal Rosai-Dorfman disease in a 26-year-old man, mimicking Lymphoplasmacyte-rich Meningioma. This case allows us to demonstrate the diagnosis pitfalls encountered in this localization.

Case report: BRAF-inhibitor therapy in BRAF-mutated primary CNS tumours including one case of BRAF-mutated Rosai-Dorfman disease

BRAF V600E oncogene mutations have been reported in multiple central nervous system (CNS) tumor types, and emerging evidence supports the use of targeted therapy in BRAF-mutated gliomas. BRAF oncogene mutations have been recently identified in Rosai-Dorfman disease (RDD)-a rare non-Langerhans cell histiocytosis. This series describes three patients from two neurosurgical centers in Ireland with BRAF V600E-mutated CNS tumors. The study participants include a 19-year-old male patient with ganglioglioma with anaplastic features, a 21-year-old male patient with CNS involvement of RDD, and a 28-year-old female patient with ganglioglioma with anaplastic features. Two patients received radiation with concurrent temozolomide before BRAF-targeted therapy. This case series describes clinical and radiological responses to BRAF-targeted therapy in BRAF V600E-mutated gliomas across multiple tumor grades and is only the second published report of response to targeted therapy in BRAF-mutated RDD. The durability of disease control with BRAF-targeted therapy was generally superior to that achieved with chemoradiation; one patient has experienced ongoing disease control for 5 years. The reported case of treatment response in BRAF-mutated RDD supports the strategy of genotyping and utilization of targeted therapy in this rare disease. The optimal sequencing of BRAF-targeted therapy in BRAF-mutated gliomas/glioneuronal tumors remains unclear, and further prospective studies are required to guide the use of genome-matched therapy in this patient population.

A Rare Case of Thymic Rosai-Dorfman Disease Mimicking Malignancy on (18)F-FDG PET/CT

Background Rosai-Dorfman disease (RDD), the massive lymphadenopathy characterized by the proliferation of sinus histiocytosis, is a relatively idiopathic benign disease with unknown etiology. We reported a rare case of thymic RDD detected by ¹⁸F-FDG PET/CT. A 23-year-old man with right-sided chest pain underwent ¹⁸F-FDG PET/CT scan, showing increased ¹⁸F-FDG uptake in an anterior mediastinal mass corresponding to a thymic lesion at an enhanced CT scan. The patient was referred to surgery with the clinical suspicion of thymic malignancy. The histological examination and immunohistochemical results confirmed RDD. Conclusions This was the first case report of RDD isolated to the thymus and initially presented with chest pain. Moreover, there was no characteristic painless neck lymphadenopathy at any stage of the disease course. Thus, for young patients with thymus mass, RDD should be considered a rare but possible diagnosis.

Strong Coexpression of Transcription Factors PU.1 and Oct-2 in Rosai-Dorfman Disease

OBJECTIVES

Rosai-Dorfman disease (RDD) is a rare disorder characterized by the accumulation of large S100 protein-positive histiocytes that typically exhibit emperipolesis. The recently reported expression of Oct-2 in RDD histiocytes led us to explore whether PU.1, a transcription factor that is required for monocyte and B-cell development, could similarly function as a diagnostic marker in RDD.

METHODS

We evaluated the expression of PU.1 and Oct-2 using immunohistochemistry in 19 patients diagnosed with RDD involving nodal, extranodal, and cutaneous sites.

RESULTS

Both PU.1 and Oct-2 were positive in all cases studied, with a strong intensity of staining in 84% of cases in which more than 50% of the lesional cells were positive. In three patients, both markers showed weak to moderate intensity of staining. Two patients had concomitant RDD and Langerhans cell histiocytosis in which PU.1 stained both types of histiocytes while Oct-2 stained only the RDD component.

CONCLUSIONS

PU.1 emerged as a robust marker with crisp nuclear staining in RDD histiocytes as well as in engulfed inflammatory cells. Strong coexpression of PU.1 and Oct-2 is a useful diagnostic marker in differentiating histiocytic/dendritic cell proliferations.

Rosai-Dorfman disease mimicking gastrointestinal tuberculosis and fungal sinusitis: A case report

Every organ can be affected by Rosai-Dorfman disease, the most common being skin and soft tissue, bone and upper respiratory tract. Here we present a Rosai-Dorfman disease patient who manifested with multiple organ involvement. A 33-year-old male presented with multiple joint pain, diarrhea, a purulent nasal discharge and sinus pain. After having serials of investigations he was misdiagnosed as having tuberculosis and fungal sinusitis. Finally, cytology from lymph node aspiration suggested Rosai-Dorfman disease. The sino nasal presentation of Rosai-Dorfman disease can be misdiagnosed as fungal sinusitis and the gastrointestinal manifestation can mimic gastrointestinal tuberculosis. Diffuse joint involvement could also be an initial manifestation of Rosai-Dorfman disease.

Hodgkinoid histiocytosis: an atypical nodal CD30 and S100-positive histiocytosis with eosinophilia

Histocytes and dendritic cells may display cytological atypia and aberrant immunophenotype even in reactive processes. Herein, we describe two cases of "Hodgkinoid histiocytosis" that show distinctive clinicopathological features, mimicking the morphologically classic Hodgkin lymphoma (CHL) but suggesting reactive histiocytic/dendritic cell proliferation in lymph nodes. Both the patients presented with peripheral lymphadenopathy and blood eosinophilia with skin manifestations. Lymph node biopsy revealed scattered large histiocytes resembling Hodgkin cells with a round or stellate shape, abundant cytoplasm, and distinct nucleoli admixed in a predominant inflammatory background. The Hodgkinoid histiocytes occasionally showed emperipolesis. They expressed CD30, S100, and PD-L1 proteins but lacked PAX5 and CD1a expressions, Epstein-Barr association, BRAF V600E mutation, and PD-L1 gene amplification. Neither of the patients showed overt progression to malignant hematopoietic neoplasms during the disease course. An identical case series of four patients has been reported to date. Both these series highlight the potential of being interpreted as CHL due to the presence of Hodgkinoid histiocytes with CD30 positivity.

Meningeal Rosai-Dorfman Disease Presenting as an Intracranial Mass - Report of a Case with Review of the Literature

Meningeal Rosai-Dorfman disease, a type of sporadic Rosai-Dorfman disease, is a rare occurrence. A few cases are reported in the English literature with an adequate immunohistochemical workup. This entity clinically and radiologically mimics either a meningeal or a parenchymal neoplasm with meningeal extension, warranting a thorough histopathologic evaluation. A broad histologic differential necessitates a detailed immunohistochemical characterization to render a correct diagnosis that has significant therapeutic and prognostic implications. Herein, we report a case of isolated meningeal Rosai-Dorfman disease in a 50-years-old human immunodeficiency virus-positive male patient with an emphasis on the histopathology, immunoprofile, and differential diagnoses.

Differential diagnosis in Rosai-Dorfman disease: A rare case of isolated hepatic presentation mimicking a metastatic tumor with positive 18-FDG uptake

Rosai-Dorfman disease (RDD) is also called sinus histiocytosis with massive lymphadenopathy, and it is caused by a histiocytic disorder with unclear etiology. It usually involves cervical lymph nodes, but it may also present with extranodal involvement. We report a rare condition of isolated hepatic RDD without nodal involvement, clinically manifested with three-month abdominal pain and tenderness of the right hypochondrium. CT- and PET-CT scans were compatible with a secondary lesion from an unknown primary tumor. Therefore, the patient underwent an atypical liver resection. Immunohistochemistry and histological results were compatible with a diagnosis of RDD. RDD is characterized by phenomena of emperipolesis, histiocytic proliferation and positive immunostaining for CD14, CD68 and S-100 protein. Cases of isolated gastrointestinal localization of RDD are particularly rare, especially in the liver. Instrumental exams might confuse RDD with other malignancies. RDD is a rare entity, which might be misdiagnosed using PET-CT due to its similarities with malignant tumors. An accurate multidisciplinary approach may help to clear diagnostic clues of this uncommon disease.

Rosai-Dorfman disease: A pathological experience from 2 tertiary care hospitals in Western Saudi Arabia

OBJECTIVES

To document the clinicopathological features of Rosai-Dorfman disease (RDD) at 2 tertiary hospitals in the western region of Saudi Arabia.

METHODS

We retrieved all cases diagnosed as RDD at King Abdulaziz University Hospital and King Faisal Specialist Hospital and Research Center, Jeddah, Saudi Arabia, diagnosed between January 2001 until June 2021.

RESULTS

A total of 13 new RDD cases were reported, including 7 nodal and 6 extranodal type. The extranodal sites included larynx, optic chiasm, dura and brain, lumbar vertebrae, and left arm soft tissue.There were 6 males and 7 females. Ages averaged 34 years and ranged from 4-56 years. A total of 2 cases were associated with Hodgkin's lymphoma, and 2 cases have been initially misdiagnosed as other entities. All patients were treated with surgical excision, and steroid was added in 3 cases. Over 2-60 months of follow-up, recurrence occurred in 2 cases.

CONCLUSION

Awareness of this entity is important for pathologists to avoid misdiagnosis. While the optimal treatment remains controversial, surgical resection is generally curative. The prognosis is good with rare recurrence. Multicenteer prospective studies are probably the best to evaluate treatment options and improve outcomes.

Acute Tubulointerstitial Nephritis in Rosai-Dorfman Disease Mimicking IgG4-related Disease

Rosai-Dorfman-Destombes disease (RDD) is a non-Langerhans cell histiocytosis characterized by the accumulation of histiocytes inside the lymph nodes or extranodally. The association between RDD and IgG4-related disease (IgG4-RD) is discussed. We herein report a case of RDD manifesting as acute tubulointerstitial nephritis mimicking IgG4-RD. The first renal biopsy showed severe tubulointerstitial nephritis with infiltration of S100-positive histiocytes and IgG4-positive plasma cells; storiform fibrosis and obliterative phlebitis were not confirmed. After prednisolone therapy, IgG4-positive cells and S100-positive histiocytes were decreased, but the IgG4/IgG ratio increased despite clinical improvement. These findings indicated extranodal RDD in the kidney presenting as tubulointerstitial nephritis.

[Magnetic Resonance Imaging Manifestations of Rosai-Dorfman Disease in Central Nervous System]

Objective To investigate the clinical and magnetic resonance imaging(MRI) manifestations of Rosai-Dorfman disease(RDD) in central nervous system. Method The clinical and MRI data of 5 cases of RDD in central nervous system confirmed by pathology in the PLA General Hospital were analyzed retrospectively. Results The 5 cases included 4 males and 1 female,aged(39.8±21.7) years on average.Among them,4 cases were located in the intracranial area and 1 case in the thoracic spinal canal.The lesion showed isointense signal on T₁ weighted image and iso,slight-hypo,and slight-hyperintense signals on T₂ weighted image,and it presented intensively homogeneous enhancement in contrast-enhanced MRI.Two cases showed compressed brain area with edema around the left parietal and left frontotemporal dura,thickening and enhancement in the adjacent dura,and dural tail sign.Three cases presented bone destruction in adjacent diploe and thoracic vertebrae.One case showcased slight-hypo perfusion of the left parietal dura in arterial spin labeling. Conclusions RDD lesion usually appears as iso,slight hypo and slight hyper-intense signals on T₂ weighted image and presents intensively homogeneous enhancement in contrast-enhanced MRI.The disease may involve the adjacent bone and the lesion shows slight hypo-perfusion on perfusion images.The MRI manifestations of RDD are characteristic,which are helpful for preoperative diagnosis and evaluation of RDD.

Cyclin D1 expression in Rosai-Dorfman disease: A near constant finding that is not invariably associated with MAPK/ERK pathway activation

Activating mutations in the MAPK/ERK pathway have been shown in nearly half of cases of Rosai-Dorfman disease (RDD). Cyclin D1, a key cell cycle regulator, constitutes a major downstream target of the MAPK/ERK pathway. In this study, we aim to further understand the pathogenesis of RDD by assessing the lesional histiocytes for cyclin D1, p-ERK, Ki-67 and BCL2 by immunohistochemistry We assessed 35 samples of RDD and a control group of histiocyte-rich reactive lesions. Cyclin D1 was expressed in about 90% of cases of RDD. Cyclin D1 was positive in 25-95% (median, 85%) of lesional histiocytes, was moderately/strongly expressed in 97% of cyclin D1-positive cases, and was significantly higher than in control specimens. p-ERK was positive in 16 of 30 (53%) cases of RDD and was negative in all controls. Whereas all p-ERK-positive RDD cases had concurrent cyclin D1 expression, over a third of cyclin D1-positive cases were negative for p-ERK. Ki-67 was low in RDD (median, 3%). BCL-2 was positive in lesional histiocytes in nine of 10 RDD cases assessed and was negative Overall, these findings point to unexpected, potential roles of these molecules in the pathogenesis of RDD. Overexpression of cyclin D1 in the absence of ERK phosphorylation in a subset of RDD cases opens the possibility of oncogenic mechanisms bypassing ERK, and supports the notion that cyclin D1 overexpression in RDD is multifactorial. Moreover, the observed lack of correlation between cyclin D1 with Ki-67 proliferative index suggests that prosurvival actions of cyclin D1 are, at least in part, cell-cycle independent. Finally, expression of BCL-2 and the low Ki-67 index suggest that RDD might be driven by anti-apoptotic rather than pro-proliferative oncogenic mechanisms.

Rosai-Dorfman disease. A legacy of Professor Rosai that is still not exploited completely

Rosai-Dorfman disease (RDD) is a rare form of non-Langerhans cell histiocytosis described by Rosai and Dorfman in 1969. It is a fascinating disease characterized by accumulation of large, pale histiocytes, frequently showing the emperipolesis phenomenon. The variety of pathological aspects and the spectrum of different clinical forms were deeply investigated by Prof. Rosai. Despite recent advancements in the dissection of pathogenetic mechanisms of RDD, with the identification of gene mutations in the MAP kinase pathway, several biological and clinical aspects of this disease remains to be elucidated: this is one of the Prof. Rosai's legacies.

The contributions of Juan Rosai to testicular pathology with personal remembrances

The authors summarize their personal interactions with someone for whom they had unbounded admiration, Dr. Juan Rosai. This varied from daily review of cases, to sharing the platform at meetings, being under his tutelage as an author, and co-directing postgraduate courses. These all highlighted the remarkable knowledge of medicine Dr. Rosai had, imparting as he did diagnostic pearls and remarks on the literature including the history of our discipline, often laced with a well-honed sense of humor. The contributions he made to the pathology of the testis are then considered beginning with his role in highlighting a tumor, at the time not particularly well publicized, spermatocytic seminoma. He wrote two major papers on it, one on standard clinical and pathologic aspects, and one on its ultrastructure. The first was associated with his diligent investigation of a prior paper reporting an unusually high number of malignant examples of this tumor but on review that was explained by their representing malignant lymphoma. The organizational skills of Dr. Rosai, and attention to detail, were second to none and shown perhaps most notably with his organizing many courses, but they were also illustrated early in his career when he moderated a symposium on germ cell tumors of the testis which laid the framework for the classification and nomenclature of premalignant lesions. Finally, his almost career-long interest in the entity he codiscovered, Rosai-Dorfman disease, was associated with his reporting testicular involvement by that disorder in his later years. This giant figure in pathology will stand forever in the top tier with other greats who have contributed to the field.

Ophthalmic histiocytic lesions: a baseline demographic and clinicopathological study of 28 cases from two eye centers

PURPOSE

Ophthalmic histiocytic lesions comprise a heterogeneous rare group of disorders that are characterized by an abnormal proliferation of histiocytes and may affect all age groups of both sexes. The aim of this study was to highlight the basic demographic, clinical, and histopathological characteristics of this rare group of diseases in ophthalmic practice, which has not been previously studied in this area. Only individual cases have been previously reported.

METHODS

This was a retrospective study of all biopsied ocular and periocular histiocytic lesions from two centers, King Khaled Eye Specialist Hospital (KKESH) and King Abdulaziz University Hospital (KAUH) in Riyadh, Saudi Arabia, from January 1993 to December 2018. The histopathological diagnosis was confirmed, and the cases were re-classified by reviewing all histopathological slides. The corresponding demographic and clinical data were analyzed. A relevant literature review was also carried out for comparison of our collected analyzed data to published data and to draw our own conclusions.

RESULTS

A total of 34 ocular/periocular histiocytic lesions in 28 patients who were mostly Saudis (92.9%) were included. The male-to-female ratio was 4:3. The median age at presentation was 6.4 years (range: 2.8-35 years). Twenty-two patients had unilateral involvement, and six patients had bilateral lesions. In patients with Langerhans cell histiocytosis (LCH; L group), the most common presenting findings were eyelid swelling (75%), periocular tenderness (37.5%), proptosis/globe displacement (37.5%) eyelid erythema (25%), and orbital pain (12.5%). In patients with Rosai Dorfman disease (RDD; R group), proptosis/globe displacement occurred in all patients and 80% had decreased vision. Patients in the C group (Cutaneous non-LCH histiocytoses) had variable clinical features because of the different locations of the histiocytic lesions, with the majority involving the eyelids (66.7%). Diagnosis was accurately reached clinically in 38.8%, 33.7%, and 46.7% of patients in the L, C, and R groups, respectively. Overall, the clinical diagnosis was in concordance with the histopathologic diagnosis in 14 out of 34 lesions (41.2%).

CONCLUSIONS

Histiocytic disease is more likely to be overlooked clinically owing to its rarity. In the C group, juvenile xanthogranuloma (JXG) was the most commonly encountered histiocytic lesion and had a tendency to present at a later age with extremely rare intraocular involvement in contrast to previously published reports. The median age at presentation was higher in group R. All patients in group L had strictly unilateral disease, while RDD (group R) was most commonly bilateral. Future research on genetic aspects, management, and prognosis is necessary.