Rosai-Dorfman disease or sinus histiocytosis with massive lymphade nopathy (SHML) is a rare benign disorder of uncertain aetiology. The condition was first described in 1969 (Rosai and Dorfman, 1969) and a further account in 1972 (Rosai and Dorfman. 1972) described the clinical and pathological features. The disease typically presents in young people with massive,painless cervical lymphadenopathy and may be accompanied by malaise, fever and weight loss. Extranodal disease occurs in 43 per cent of patients and most commonly involves the skin, nasal cavity and paranasal sinuses. The condition may present to the ear, nose and throat (ENT) department in a number of ways but isolated salivary gland disease is relatively unusual since patients presenting with salivary gland involvement possess additional extranodal disease in the majority of cases.

Our report describes an atypical presentation of SHML and the particular importance lies in the unusual appearance of the fine needle aspirate which initially suggested a malignancy, previously not described in cytological specimens in cases of SHML.

Case Report

A 71-year-old male was referred to ENT outpatients with a left-sided facial swelling. The patient had been aware of a painless lump in the pre-auricular area tor some months, but an increase in size in the previous month had precipitated his referral. There were no associated symptoms and the patient was a non-smoker with no relevant past medical history. On physical examination a round mobile swelling approximately 1.5cm in size was present over the pre-auricular area. The parotid duct and facial nerve function were both normal. The mass was believed most likely to represent a pleomorphic adenoma and a fine needle aspirate was performed for cytological examination. Subsequent computed tomography (CT) scan confirmed a welt-defined solid mass within the superficial lobe of the left parotid gland and enhanced sections through the neck showed no lymph node enlargement. The routine full blood count and serum estimation of electrolytes and liver function were within normal parameters. The patient underwent a superficial parotidectomy and the specimen was sent for histological examination.

Pathological Findings

Examination of the fine needle aspirate specimen from the parotid gland mass revealed numerous epithelioid cells showing nuclear atypia and containing mitotic figures. These cells were admixed with lymphocytes, plasma cells and normal parotid gland acini. The appearances of the atypicat epithelioid cells were interpreted as suspicious of malignancy and biopsy was advised.

The excised portion of parotid gland measured 60*45*5mm. Sectioning the parotid tissue revealed a 15 mm diameter fairly well-defined sott, white and yellow lesion. Microscopic examination revealed that this lesion was at least partly contained within a lymph node, with a partial fibrous capsule, an underlying subcapsular sinus and peripheral foci of small lymphoid cells. However, the majority of the lymph node architecture was effaced by sheets of epithelioid histiocytes dilating the nodal sinuses and exhibiting erythrophagocytosis and lymphophagocytosis (engulfment of intact erythrocytes and lymphocytes within the cytoplasm of epithelioid histiocytes, also termed emperipolesis), together with scattered small foci of necrosis. Immunohistochemical staining revealed that the histiocytes labelled positively with the MAC 387 antibody as well as with anti-bodies to S100 protein and CD68. The appearances were interpreted as those of sinus histiocytosis with massive lymphade-nopathy (SHML) (Rosai-Dortman disease) occurring within an intraparotid lymph node.

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