Lung Involvement in Destombes-Rosai-Dorfman Disease: Clinical and Radiological Features and Response to the MEK Inhibitor Cobimetinib

Treatment of Langerhans Cell Histiocytosis and Histiocytic Disorders: A Focus on MAPK Pathway Inhibitors

Histiocytic disorders are rare diseases defined by the clonal accumulation of a macrophage or dendritic cell origin. These disorders include Langerhans cell histiocytosis, Erdheim-Chester disease, juvenile xanthogranuloma, malignant histiocytoses, and Rosai-Dorfman-Destombes disease. These histiocytic disorders are a diverse group of disorders with different presentations, management, and prognosis. This review focuses on these histiocytic disorders and the role of pathological ERK signaling due to somatic mutations in the mitogen--activated protein kinase (MAPK) pathway. Over the last decade, there has been growing awareness of the MAPK pathway being a key driver in many histiocytic disorders, which has led to successful treatment with targeted therapies, in particular, BRAF inhibitors and MEK inhibitors.

Outcomes After Treatment With Cobimetinib in Patients With Rosai-Dorfman Disease Based on KRAS and MEK Alteration Status

Importance

Rosai-Dorfman disease (RDD) is a rare histiocytic neoplasm with recent studies showing alterations in the MAPK pathway, most commonly in the KRAS and MEK genes in about 40% of patients. Reports on the use of MEK-inhibitor therapy in RDD have been limited to small case studies. There are no approved treatments for this neoplasm, and therefore patients with RDD need efficacious treatments.

Objective

To study the outcomes after treatment with cobimetinib based on MAPK pathway alterations in patients with RDD.

Design, Setting, and Participants

This retrospective cohort study conducted at 2 tertiary care centers included patients with RDD who underwent treatment with cobimetinib between January 1, 2013, and December 1, 2021. Cobimetinib was administered at a dosage of 20 to 60 mg orally once daily as a single agent for 21 days in a 28-day cycle. Pathology was centrally reviewed. Response assessment was centrally conducted and was based on the established positron emission radiography response criteria used for clinical trials of targeted therapies in histiocytosis.

Main Outcomes and Measures

Main outcomes were overall response rate (ORR), progression-free survival (PFS), adverse events (AEs) of cobimetinib in the entire cohort, and ORRs and PFS based on MAPK pathway alterations in patients with RDD.

Results

A total of 16 patients (median [range] age at cobimetinib initiation, 57 [31-74] years; 11 [69%] women) were included in the study. The median follow-up duration was 19.0 months (95% CI, 8.4-27.8 months). The ORR was 63% (n = 10), including 5 complete responses and 5 partial responses. Somatic alterations in the KRAS or MEK genes were detected in 8 (50%) patients. Patients with KRAS or MEK alterations had significantly higher ORR (88% vs 38%; P = .03), deeper responses (complete responses among responders: 71% vs 0%; P = .002), and better PFS (at 1 year, 100% vs 29% were free from progression or death, respectively; P < .001) compared with those without such alterations. Grade 2 or higher AEs occurred in 12 (75%) patients, and 9 (56%) required dose reduction or temporary/permanent treatment discontinuation due to AEs.

Conclusions and Relevance

In this cohort study, treatment with cobimetinib was associated with positive outcomes in KRAS- or MEK-variant RDD. However, AEs requiring dose modifications were common.

68Ga-FAPI and 18F-FDG PET/CT Images of a Patient With Rosai-Dorfman Disease With Liver Involvement

ABSTRACT

Rosai-Dorfman disease is a rare non-Langerhans cell histiocytosis that is histopathologically characterized by the accumulation of CD68-positive and S100-positive histiocytes. The pathological changes are mostly discovered in lymph nodes. We report a case of Rosai-Dorfman disease with liver and bone marrow involvement. In this case, 18F-FDG PET/CT revealed FDG avidity in multiple lymph nodes, liver, and bone marrow. 68Ga-FAPI PET/CT showed higher uptake of 68Ga-FAPI than that of 18F-FDG in the same lesions. The findings of 68Ga-FAPI PET/CT in this patient highlighted the potential value of 68Ga-FAPI for staging in Rosai-Dorfman disease.

Rosai-Dorfman Disease between Proliferation and Neoplasia

Rosai-Dorfman disease (RDD) is a rare myeloproliferative disorder of histiocytes with a broad spectrum of clinical manifestations and peculiar morphologic features (accumulation of histiocytes with emperipolesis). Typically, the patient with RDD shows bilateral painless, massive cervical lymphadenopathy associated with B symptoms. Approximately 43% of patients presented with extranodal involvement. According to the 2016 revised histiocytosis classification, RDD belongs to the R group, including familial and sporadic form (classical nodal, extranodal, unclassified, or RDD associated with neoplasia or immune disease). Sporadic RDD is often self-limited. Most RDD needs only local therapies. Nevertheless, a small subpopulation of patients may be refractory to conventional therapy and die of the disease. Recent studies consider RDD a clonal neoplastic process, as approximately 1/3 of these patients harbor gene mutations involving the MAPK/ERK pathway, e.g., NRAS, KRAS, MAP2K1, and, rarely, the BRAF mutation. In addition to typical histiocytic markers (S100/fascin/CD68/CD163, etc.), recent studies show that the histiocytes in RDD also express BCL-1 and OCT2, which might be important in pathogenesis. Additionally, the heterozygous germline mutation involving the FAS gene TNFRSF6 is identified in some RDD patients with an autoimmune lymphoproliferative syndrome type Ia. SLC29A3 germline mutation is associated with familial or Faisalabad histiocytosis and H syndrome.

Neurology and the histiocytoses: a case of Rosai-Dorfman-Destombes disease

The histiocytoses are a group of rare disorders characterised by the accumulation of neoplastic or non-neoplastic activated histiocytes in various tissues. Phenotypes vary widely from cutaneous lesions or lymphadenopathy that regress spontaneously to disseminated disease with poor prognosis. Neurological symptoms can be a presenting feature or appear during the course of disease. We present a challenging diagnostic and management case of Rosai-Dorfman-Destombes disease in a 48-year-old woman with a relapsing, partially steroid-responsive syndrome comprising patchy, non-length-dependent radiculoneuropathy with diffuse pachymeningitis and widespread systemic disease, and recent dramatic response to novel mitogen-activated kinase pathway inhibition. We discuss the clinical characteristics, diagnosis, recent breakthroughs in pathogenesis and emerging treatment options for Rosai-Dorfman disease and for the histiocytoses with neurological sequelae, including Langerhans cell histiocytosis and Erdheim-Chester disease.

Histiocytic Neoplasms, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology

Histiocytic neoplasms are rare hematologic disorders accounting for less than 1% of cancers of the soft tissue and lymph nodes. Clinical presentation and prognosis of these disorders can be highly variable, leading to challenges for diagnosis and optimal management of these patients. Treatment often consists of systemic therapy, and recent studies support use of targeted therapies for patients with these disorders. Observation ("watch and wait") may be sufficient for select patients with mild disease. These NCCN Guidelines for Histiocytic Neoplasms include recommendations for diagnosis and treatment of adults with the most common histiocytic disorders: Langerhans cell histiocytosis, Erdheim-Chester disease, and Rosai-Dorfman disease.

Rosai–Dorfman Disease: Breast Involvement—Case Report and Literature Review

Background and objectives: Rosai–Dorfman disease (RDD) is a type of histiocytosis that usually appears in young adults or children as bilateral cervical lymphadenopathy, but extranodal involvement in not uncommon. Although the pathogenesis is not entirely elucidated, recent studies showed a possible neoplastic process. Materials and methods: Our manuscript presents a rare case of Rosai–Dorfman disease of the breast, the management of this rare case, and a literature review. There are few cases reported of RDD of the breast (around 90 globally reported cases); the data is poor, and the management not yet standardized for these cases. The case reported here shows the importance of correct breast investigation, breast imaging, and ultrasound-guided biopsy that provided an accurate diagnosis and guided further management. Results: Although RDD of the breast was rarely presented as bilateral disease in other case reports, our case showed bilateral breast disease with the suspicion of breast cancer on imaging. Pathology and immunohistochemistry were of critical importance and showed a specific pattern for histiocytosis. A multidisciplinary approach was taken into consideration for these cases in order to establish the approach. Some patients underwent surgery, but watchful waiting and close follow-up were the preferred approach. Conclusions: RDD of the breast is a rare form of histiocytosis, with fewer than 100 globally published cases. Although the management of this disease is not established yet by guidelines, a follow-up approach should be enough for these patients, and surgery might be overtreatment. Mortality from RDD is very low due to comorbidities. A multidisciplinary team decision is important, and abstinence might significantly benefit these patients.

Histiocytic disorders

The historic term 'histiocytosis' meaning 'tissue cell' is used as a unifying concept for diseases characterized by pathogenic myeloid cells that share histological features with macrophages or dendritic cells. These cells may arise from the embryonic yolk sac, fetal liver or postnatal bone marrow. Prior classification schemes align disease designation with terminal phenotype: for example, Langerhans cell histiocytosis (LCH) shares CD207+ antigen with physiological epidermal Langerhans cells. LCH, Erdheim-Chester disease (ECD), juvenile xanthogranuloma (JXG) and Rosai-Dorfman disease (RDD) are all characterized by pathological ERK activation driven by activating somatic mutations in MAPK pathway genes. The title of this Primer (Histiocytic disorders) was chosen to differentiate the above diseases from Langerhans cell sarcoma and malignant histiocytosis, which are hyperproliferative lesions typical of cancer. By comparison LCH, ECD, RDD and JXG share some features of malignant cells including activating MAPK pathway mutations, but are not hyperproliferative. 'Inflammatory myeloproliferative neoplasm' may be a more precise nomenclature. By contrast, haemophagocytic lymphohistiocytosis is associated with macrophage activation and extreme inflammation, and represents a syndrome of immune dysregulation. These diseases affect children and adults in varying proportions depending on which of the entities is involved.

Histiocytosis

Histiocytoses constitute a heterogeneous group of rare disorders, characterised by infiltration of almost any organ by myeloid cells with diverse macrophage or dendritic cell phenotypes. Histiocytoses can start at any age. Diagnosis is based on histology in combination with appropriate clinical and radiological findings. The low incidence and broad spectrum of clinical manifestations often leads to diagnostic delay, especially for adults. In most cases, biopsy specimens infiltrated by histiocytes have somatic mutations in genes activating the MAP kinase cell-signalling pathway. These mutations might also be present in blood cells and haematopoietic progenitors of patients with multisystem disease. A comprehensive range of investigations and molecular typing are essential to accurately predict prognosis, which can vary from spontaneous resolution to life-threatening disseminated disease. Targeted therapies with BRAF or MEK inhibitors have revolutionised salvage treatment. However, the type and duration of treatment are still debated, and the prevention of neurological sequelae remains a crucial issue.

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.

Management and outcomes of sinus histiocytosis with massive lymphadenopathy (Rosai Dorfman Disease)

Sinus histiocytosis with massive lymphadenopathy (Rosai Dorfman Disease [RDD]), is a rare, benign but clinically heterogeneous histiocytic disorder. Our aims were to analyze the clinical characteristics of the disease and explore the outcomes of patients with RDD followed at our institution. Between January 2000 and February 2019, there were 15 patients with a pathologically confirmed diagnosis of RDD. Median age at diagnosis was 48 years old (range 26-78). The majority (87%, n = 13) of the patients had extranodal disease. Frontline approaches included surgical intervention/complete excision (n = 5, 33%), rituximab monotherapy (n = 5, 33%), observation (n = 3, 20%), and radiation (n = 2, 13%). Two of the five patients underwent surgical excision and were subsequently treated with rituximab. Of the 7 patients who were given rituximab, 64% remained progression free 24 months after the initial rituximab administration. Our review parallels previous reports and highlights rituximab as a favorable option for therapy if ineligible for surgery or radiation.