Pinworm infection masquerading as colorectal liver metastasis

Abstract

Enterobius vermicularis is responsible for a variety of diseases but rarely affects the liver. Accurate characterisation of suspected liver metastases is essential to avoid unnecessary surgery. In the presented case, following a diagnosis of rectal cancer, a solitary liver nodule was diagnosed as a liver metastasis due to typical radiological features and subsequently resected. At pathological assessment, however, a necrotic nodule containing E vermicularis was identified. Solitary necrotic nodules of the liver are usually benign but misdiagnosed frequently as malignant due to radiological features. It is standard practice to diagnose colorectal liver metastases solely on radiological evidence. Without obtaining tissue prior to liver resection, misdiagnosis of solitary necrotic nodules of the liver will continue to occur.

Liver and Bile Duct Infections

“…430 Subcapsular nodules in the liver may be found at the time of surgery or may be radiologically detected during staging of patients with carcinoma, leading to misdiagnosis as metastases. 431,432 Histologic examination shows large necrotic nodules with surrounding histiocytic reaction and fibrosis, hyalinizing granulomas, or calcifying granulomas; the lesions contain remnants of pinworms with characteristic lateral alae and multiple ova. [430][431][432][433]…”