Clinical History
The patient was sent to our department for a magnetic resonance (MR) examination of the orbit because of bilateral painless progressive proptosis, with limited extraocular muscle movement, for a few months. He was affected by Rosai-Dorfman disease (RDD) – diagnosed three years ago by biopsy – in the humerus and tibias (Fig.1).
Imaging Findings
MR images showed bilateral intraconal ocular lesions, isointense in T1-weighted images (Fig. 2) and hypointense to isointense in T2-weighted images (Fig. 3; probably due to free radicals released by inflammatory macrophages).
Right orbit: MR underlined two lesions; the major one of 2.7 cm with infiltration of the medial rectus muscle and compression of superior rectus muscle, optic nerve and lamina papyracea. The second lesion, 0.8 cm in diameter, localized anteriorly between medial rectus muscle and optic nerve.
Left orbit: MR showed two lesions with the same characteristics: one lesion, 2.1 cm in diameter, along the lateral rectus muscle; another lesion, 1.1 cm in diameter, at the external ocular insertion of the lateral rectus muscle.
There was no involvement of the lacrimal glands.
Further disease foci were identified around the foramen ovale and involving the posterior wall of the sphenoid sinus and clivus (Fig. 2-4).
All these lesions enhanced following contrast medium administration (Fig. 4).
Discussion
RDD is a rare disorder characterised by nonmalignant proliferation of distinctive histiocytes within lymphnode sinuses and other extranodal sites [1]. RDD may present in children and young adults (80% of the patients are aged 20 years or younger at onset) with fever, leukocytosis and polyclonal hypergammaglobulinaemia.
The exact aetiology is unknown: viruses like Human Herpes Virus 6, Klebsiella, Epstein-Barr virus, Cytomegalovirus or Brucella as a causative agent have been postulated [1].
Most patients are characterised by bilateral painless massive lymphadenopathy (involvement of the cervical region in up to 90% of patients) with or without constitutional manifestation. About 43% of patients have extranodal symptoms: in decreasing order of frequency are skin, nasal cavity and paranasal sinus, eyelid, orbit (bilateral involvement is rarer than the unilateral), bone, salivary gland and central nervous system [1]. Involvement of multiple extranodal sites is not unusual and they can be the predominant or exclusive manifestations.
Ocular disease is relatively uncommon (8.5%), and most cases have presented as lymphoproliferation in the soft tissues of the orbit, eyelids and rarely uveitis [2]. Epibulbar mass as isolated finding of extranodal RDD is very rare, generally it is associated with concurrent systemic disease.
The clinical profile of these patients is painless progressive proptosis and a palpable well-defined, nontender orbital mass. Diffuse conjunctival congestion and restricted ocular motility could be noted.
The diagnosis remains a disorder primarily defined by pathologic manifestations and its histopathologic features: large voluminous histiocytes with a vacuolated eosinophilic cytoplasm containing small mature lymphocytes (emperipolesis or lymphocytophagocytosis) and lying against a mixed inflammatory background of lymphocyte, plasma cells and occasional neutrophils. These histiocytes were immunoreactive to the S-100 antibody but not for CD1a, which is diagnostic [3].
As RDD is a systemic disease, whole-body imaging may be useful for staging—including nodal and extranodal involvement—and follow-up of disease [4] without the need of radiation or intravenous contrast agent.
RDD usually follows a course of spontaneous regression and recovery; however, in a small percentage of cases, the disease may be persistent and progressive, with localization of disease at the kidney, lower respiratory tract or liver [1].
The treatment of orbital manifestations aims to control the functional and cosmetic appearance. For orbital involvement, being cosmetically disturbing and surgically accessible, surgical excision can be considered as a first-line therapy and may be curative [5]. Massive or recurrent orbital disease or significant residual lesion following surgical debulking may be treated with systemic corticosteroids, chemotherapy (vinca alkaloids) or radiotherapy.
Differential Diagnosis List
Bilateral ocular involvement of Rosai-Dorfman disease.
Lymphoma
Melanoma
Sarcoma
Metastasis
Tyreopathy
Myositis
Final Diagnosis
Bilateral ocular involvement of Rosai-Dorfman disease.
