Mass-forming extramedullary haematopoiesis of the liver mimicking metastases of lung cancer at initial presentation – a case report and literature review

Abstract

Extramedullary haematopoiesis (EMH) of the liver is usually a diffuse process. However, it occasionally forms focal masses with non-specific imaging features, which may mimic metastatic deposits, especially in patients with active or previous malignancy.1 We report the case of a 79-year-old male ex-smoker who presented with shortness of breath and weight loss. Computed tomography showed two spiculated lung lesions and two hypoattenuating liver lesions, which were interpreted as primary lung tumours with liver metastases. Fine-needle aspiration cytology of the larger liver lesion unexpectedly revealed EMH without evidence of malignancy. Subsequent biopsies of the lung lesions established the diagnosis of primary lung adenocarcinoma. Disease stage was revised down because of the findings in the liver. There are a few previous case reports of mass forming EMH in the liver and at other sites mimicking metastases. It is postulated that EMH may develop in patients with solid malignancy, including lung cancer, due to secretion of haematopoietic growth factors by the primary tumour.2 Pathologists should be aware of this rare but recognised presentation of EMH.