Murine (endemic) typhus is a notifiable disease in Hong Kong, but its diagnosis can be difficult. We report a case of murine typhus in a middleaged man who presented with persistent fever, headache, and skin rash 2 weeks after returning from a visit to China. The diagnosis of murine typhus requires a high index of suspicion for a febrile patient with a history of potential exposure to the disease vector (rat flea) in an endemic area. The importance of early recognition lies in the potential for early therapeutic intervention, leading to decreases in morbidity and duration of stay in hospital.

We report on two patients with diabetic muscle infarct, a painful musculoskeletal disorder complicating longstanding diabetes with established microangiopathy. Both patients had renal failure that was treated by dialysis. The underlying pathophysiological process was considered to be an arterial vascular event mediated through ischaemia-reperfusion injury. Clinicians should be alert to this condition. T2-weighted magnetic resonance imaging was valuable in establishing the diagnosis.

A rare case of pyothorax-associated large B-cell lymphoma occurring in Hong Kong is reported. The patient was a 64-year-old Chinese male who presented with shortness of breath and pleuritic pain. Radiological examination revealed left pleural thickening associated with bilateral pleural effusion. Open biopsy of the thickened parietal pleura revealed occasional large malignant lymphoid cells of B lineage admixed with fibrin and hyalinised fibrous tissue. These lymphoma cells were shown to harbour both Epstein-Barr virus and human herpesvirus type 8 by in situ hybridisation and immunohistochemical study, respectively. There was no associated lymphadenopathy and hepatosplenomegaly. The clinicoradiological presentation and pathological findings thus fulfilled the criteria of the so-called pyothorax-associated large B-cell lymphoma. Awareness of this rare entity, together with diligent histological examination and proper application of ancillary investigative techniques, are essential for making a correct diagnosis. The co-infection with Epstein-Barr virus and human herpesvirus type 8 in this case also suggests a possible pathogenetic relationship between pyothorax-associated large B-cell lymphoma and primary effusion lymphoma.

A 50-year-old Chinese woman with a chronic 20-year history of ataxic gait associated with dry eyes and mouth, was admitted to hospital after a single episode of syncope. Magnetic resonance imaging scans showed a large left frontal hypodense lesion suggestive of a glioma. Craniotomy was performed and the lesion excised, with histology showing only infarcted tissue and no malignant cells. Further diagnostic evaluation revealed that the patient had primary Sjogren’s syndrome, with demyelinating polyneuropathy. In the absence of risk factors for stroke, it was considered likely that the cerebral infarct was secondary to autoimmune-related vasculitis. Functional neuroimaging, such as magnetic resonance spectroscopy, should be considered in evaluating doubtful or unusual brain lesions in patients with autoimmune disease.

We report the case of a 71-year-old Japanese woman with mixed connective tissue disease and increased levels of platelet-associated immunoglobulin G. After administration of oral prednisolone, platelet-associated immunoglobulin G levels decreased with a simultaneous increase in the number of platelets, suggesting that the thrombocytopenia observed in this patient was mediated by immune mechanisms. This is the first reported case of increased platelet-associated immunoglobulin G levels in a patient with mixed connective tissue disease.