P-L07 Nematode infection mimicking Liver metastasis from previous Melanoma

Background Malignant melanoma is known to metastasise to the liver. In the absence of any other disease spread it is prudent to resect these lesions. This case highlights how certain pathology can masquerade as liver metastases. Here we present a case of a gentleman previously diagnosed with malignant melanoma in 2016. He had previous liver resection for metastatic disease in 2017. Surveillance MRI picked up what was assumed to be a further metastatic deposit in the right lobe of the liver. Patient underwent resection, and subsequent histological analysis has shown this to be a worm cast from a parasitic infection. Methods Review of the current literature reveals just one previous case of nematode infection masquerading as liver metastasis making this a very unusual and rare finding at operation. We have undertaken review of patients imaging and histopathological specimens as well as seeking expert opinion from the infectious diseases centre in London Results Images were reviewed in HPB MDT and the suggestion was that this was a new malignant lesion in right lobe of liver. At time of operation the lesion had slightly odd appearance on USS. Specimen was sent for histological analysis and this showed no features to suggest malignant melanoma. On further examination there appeared to be a collection of hyalinised structures suspicious for parasitic infection. The specimen was sent to Guys for further evaluation. This confirmed that this was likely a helminth nematode resulting in a necrotic liver nodule Conclusions This presentation is highly unusual and review of the literature demonstrates only 1 previous case to date. The differential for liver lesions is broad and nematode infection should be included. However on a background of previous liver metastases it would not be high on the differential list. It is important that we consider this in future and ensure to clarify risk factors for nematode infection, none of which this patient had. Highlights that despite advancement in imaging it is still only after surgical resection we can be sure of the aetiology.