Primary intraosseous Rosai-Dorfman disease treated with a novel image-guided approach - A case report

INTRODUCTION

Rosai–Dorfman disease (RDD) is a rare, benign histiocytic disorder, first described by Rosai and Dorfman in 1969.^[1-4] It typically presents with massive cervical lymphadenopathy, extranodal involvement is seen in nearly 43% of cases.^[5] Primary intraosseous RDD without nodal involvement is exceptionally rarer and presents a diagnostic and therapeutic challenge due to its nonspecific imaging findings and limited clinical awareness. We present a unique case of solitary intraosseous acetabular RDD, managed successfully with image-guided intra-lesional corticosteroid injection - a novel, minimally invasive therapeutic approach.

CASE REPORT

A 20-year-old female presented in October 2020 with pain over the right hip for 3 months, inability to bear weight on the affected limb and was confined to wheelchair. On examination, no palpable mass, erythema, or regional lymph nodes were noted. Tenderness was noted on internal rotation in the right hip.

Imaging findings

Radiograph showed an ill-defined lytic lesion in the right peri-acetabular region [Figure 1a]. Magnetic resonance imaging (MRI) showed an ill-defined destructive bony lesion in the right acetabulum appearing hyperintense on T2/short tau inversion recovery image (STIR), hypointense on T1-weighted imaging, and showing heterogeneous post-contrast enhancement [Figure 1b-f]. Fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (CT) showed an intensely FDG-avid destructive lesion with an associated soft tissue component involving the posterior column of the right acetabulum and no other lesion [Figure 1g-m]. Imaging differential diagnosis includes eosinophilic granuloma, Ewing’s sarcoma, metastasis, and primary bone lymphoma.

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Figure 1:

(a) Plain radiograph of right hip joint (Antero-posterior view - AP view) on presentation showed an ill-defined lytic lesion in right peri-acetabular region (yellow block arrow); (b) Coronal T1-weighted MRI shows ill-defined hypointense lesion in right acetabulum (yellow block arrow); (c) Coronal T2-weighted MRI demonstrates hyperintense lesion (yellow block arrow) and (d) Coronal STIR MRI shows a hyperintense lesion in the right acetabulum (yellow block arrow); (e and f) Coronal and Sagittal T1 post contrast MRI, respectively, show heterogeneous lesional enhancement (yellow block arrow) with associated enhancing soft tissue component (red block arrow); (g-l) FDG PET-CT fusion images demonstrate intensely FDG-avid lesion (yellow block arrows) with cortical destruction and soft tissue extension; (m) Whole-body PET MIP image shows solitary FDG-avid lesion in the right acetabulum (yellow block arrow) with no other metabolically active focus.

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Histopathology

CT-guided biopsy of destructive lesion in the right acetabulum was consistent with Rosai–Dorfman disease (RDD). Low-power hematoxylin and eosin staining showed mixed inflammatory infiltrates with numerous large histiocytes and abundant eosinophilic cytoplasm. Higher magnification showed emperipolesis, which is an uncommon biological process where cell penetrates another living cell; here, the cells can exist as viable cells within another cell and can exit anytime without causing any structural or functional abnormalities for either of them [Figure 2].

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Figure 2:

(a) Hematoxylin and eosin (H&E) (10× magnification) showing mixed inflammatory infiltrate with numerous large histiocytes and abundant eosinophilic cytoplasm (red marked area). Immunohistochemistry (IHC) images (b) (400× magnification) and (c) (100× magnification) - demonstrating CD68 histiocytes and emperipolesis—which is an uncommon process in which intact lymphocytes are engulfed by histiocytes without destruction (red marked area highlights engulfed lymphocytes). (d) Immunohistochemistry (400x magnification) for S100 showing diffuse cytoplasmic positivity in histiocytes, supporting the diagnosis of Rosai–Dorfman disease.

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Treatment provided and follow-up

Treatment options described for treating RDD of bone include surgical resection and intra-lesional curettage. Considering the location of tumor in the pelvis, both these procedures entailed significant intra and post-operative morbidity and gait changes. Since RDD is a histiocytic lesion, tumor board decision was to offer a trial of intra-lesional steroid injection. Furthermore, as it was a solitary lesion, no systemic therapy was offered.

With the patient in lateral position, under general anesthesia and image guidance, “J” needle was introduced into lesion in the superior acetabular region, the wall of lesion was curetted, and 40 mg of methylprednisolone was injected into the lesion [Figure 3]. No procedural complications such as hemorrhage, infection, or adverse drug reactions were observed.

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Figure 3:

Patient in lateral position, “J” needle was introduced into lesion in the right superior acetabular region (white arrow) and methylprednisolone was injected into the lesion.

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Interestingly, the immediate post-procedure patient had a significant reduction in pain. The patient was kept on non-weight bearing for 6-week post-procedure to allow for new bone formation, subsequently allowed gradual weight bearing, and was walking without support around 3 months post-procedure. Significant symptomatic improvement noted during clinical follow-up with gradual reduction in pain (Visual Analog Scale pain scale reduced from initial 9 to present 0).

3-month post-procedure imaging showed reduction in size of lesion and the appearance of peripheral sclerosis. Follow-up MRI in April 2024 showed further reduction in size of lesion with no associated soft tissue component, demonstrating an effective response.

DISCUSSION

RDD referred to as sinus histiocytosis with massive lymphadenopathy is a rare non-Langerhans cell reactive histiocytic disorder that was first described in the literature by Destombes in 1965 and recognized by Rosai and Dorfman as a distinct clinico-pathological entity in 1969.^[1-4] Histologically, it is characterized by massive proliferation of inflammatory cells, including histiocytes containing lymphocytes and hematopoietic cells within their cytoplasm. RDD primarily involves lymph nodes; extra-nodal involvement occurs in 43% of cases, and isolated extra-nodal involvement occurs only in 23% of cases. Extra-nodal sites include skin, eyes, adnexae, paranasal sinuses, genitourinary system, central nervous system, bone, breast, soft tissues, and thyroid.^[5] In <10% of patients, bone is the secondary site of RDD. Osseous involvement without lymphadenopathy (primary bone disease) is rarer and there are only few reported cases. Primary RDD of bone is usually solitary and has been described in calvaria (31%), facial bones (22%), tibia (18%), followed by clavicle, spine, pelvis, femur, and small bones of the hands and feet.^[3,4,6,7] These usually present as lytic intramedullary lesions with sharply or poorly defined margins, usually in metaphyseal or epiphyseal locations in long bones.^[4,6,8,9]

The prognosis of intra-osseous RDD is usually good. The current treatment options for RDD vary depending on disease severity and location. Systemic corticosteroids, immune-modulatory agents, surgical resection, and intralesional curettage are commonly used. Systemic therapies may induce unwanted side effects, and surgery may not be feasible in anatomically challenging locations. To address these challenges, we report a novel, minimally invasive technique involving CT-guided intra-lesional corticosteroid injection for the treatment of intraosseous RDD.

DIFFERENTIAL DIAGNOSIS

Differential diagnosis for skeletal RDD is given in Table 1.

CONCLUSION

This case demonstrates the efficacy of a novel minimally invasive image-guided intra-lesional corticosteroid injection for the treatment of primary intraosseous RDD and offers a promising alternative for managing challenging cases in anatomically complex regions. Our patient had a favorable clinico-radiological outcome, demonstrating the efficacy of this technique in reducing lesion size and significantly improving the quality of life. In addition, the absence of complications highlights the safety profile of the technique.

TEACHING POINTS

1. Imaging in RDD can be challenging. Histopathological examination is confirmatory with characteristic features such as emperipolesis and a mixed inflammatory infiltrate containing large histiocytes.

2. Minimally invasive alternatives are important in anatomically complex sites such as the acetabulum, where surgical options carry high morbidity. Image-guided intra-lesional corticosteroid injection serves as a viable and effective treatment alternative.

3. Local corticosteroid injection can lead to significant pain relief, radiological resolution, and functional recovery without systemic side effects or procedural complications.

MCQs

1. Which of the following is a hallmark histopathological feature of RDD?

   1. Caseating granulomas

   2. Verocay bodies

   3. Emperipolesis

   4. Reed–Sternberg cells

   Answer Key: c

2. Which bone site is most commonly affected in primary osseous RDD?

   1. Tibia

   2. Facial bones

   3. Femur

   4. Calvaria

   Answer Key: d

3. Which of the following imaging findings is most characteristic of intraosseous RDD?

   1. Sclerotic lesion with sunburst periosteal reaction

   2. Lytic lesion with well-defined or sclerotic margins

   3. Ground-glass matrix with cortical expansion

   4. Blastic lesion with ivory vertebra appearance

   Answer Key: b