Teaching Case

18 months following completion of a chemoradiotherapy treatment for a T4aN3M0 oropharyngeal malignancy, a 55-year-old man attended the Emergency Department with central abdominal pain and vomiting (Figures 1 and 2A: pre-treatment MRI neck and PET-CT). He had a history of open appendectomy and a liver transplant for alcohol-related liver disease.

A CT of the abdomen showed high-grade small bowel obstruction with a transition point and circumferential mural thickening secondary to a stricturing lesion in the terminal ileum, 3 cm proximal to the ileocaecal valve (Figure 3). On retrospective review, this was not evident on the prior post-treatment PET-CT at 4 months which showed complete metabolic response at the primary site and no new sites of disease (Figure 2B).

The patient underwent an emergency laparotomy, which confirmed a 2.3 cm stricturing lesion, and a right hemicolectomy was performed. Histology showed metastatic keratinising squamous cell carcinoma. A clinical examination and imaging of the neck, chest abdomen and pelvis revealed no recurrent disease in the neck, further metastases, nor a new upper aerodigestive tract primary.

Factors increasing the risk of distant metastasis from a head and neck squamous cell carcinoma include advanced tumour and nodal stage, poor loco-regional control following treatment and high histological grade [1]. The site of the primary tumour is also influential, with hypopharyngeal cancers associated with a greater risk than other head and neck primary sites. Distant metastasis is usually clinically evident within 2 years following presentation, if not present at initial staging [1].

The lung is the most common distant metastatic site, accounting for 70-85% of distant metastases, followed by bone (15-39%) and the liver (10-30%) [1]. Abdominal metastases (usually liver) are more commonly seen in the context of concurrent disease spread to other metastatic sites, most frequently the lung [2, 3]. Small bowel metastases are rare entities, accounting for approximately 10% of all small bowel malignancies [4]. Typical primary lesions include cervix, uterus, colon, melanoma, breast and lung.

A review by Dwivedi et al. in 2010 [5] found the majority of head and neck cancers with bowel metastasis were from the larynx, with only 3 of 12 cases having an oropharyngeal primary. Since this review one further case of oropharyngeal primary with synchronous pulmonary and gastrointestinal tract metastases has been reported [6]. Predilection for metastasis to the distal small bowel, as opposed to other sites along the gastrointestinal tract, was noted by Dwivedi et al. A median time-lapse of 12 months (range 0 - 56 months) between diagnosis and intestinal metastasis presentation was reported [5]. In four of the 12 cases the metastasis became apparent after 18 months or longer, in line with the 18 month delay in the present case.

Importantly, the reported incidence of head and neck cancers in patients with a solid organ transplant is higher than that of the general population: up to 15% compared to 4% [7, 8]. Non-cutaneous head and neck cancers account for approximately 4-6% of malignancies in transplant recipients [8]. Furthermore, immunosuppression following solid organ transplant has been associated with more advanced staging at the time of presentation and a more aggressive pattern of disease. This is thought to be due to an impaired tumour surveillance mechanism by lymphocytes [8]. In the case described, no distant metastases were revealed on the post-treatment PET/CT. The unusual pattern of late spread to the bowel, bypassing the lungs, may be related to immunosuppression.