A mass growing in the neck

A healthy individual had a low-intensity car accident two years ago, with transient loss of consciousness. He was discharged with a grade I sprain. Months later, he reported sensation of a foreign body in the neck slowly growing but without pain or other symptoms.

An initial approach to evaluate the neck was made using a CT scan, which demonstrated a lytic lesion with sclerotic borders at the C7 vertebral level and associated mass effect. Further characterization was obtained using an MRI, which revealed a lesion with heterogeneous content and mixed signal intensity. The lesion exhibited hyperintensity on both T1- and T2-weighted sequences compared to the spinal cord with peritumoral oedema, and there were punctuated areas of signal void on the susceptibility-weighted sequence which correspond to haemorrhage. The lesion was isointense to the spinal cord on the FLAIR sequence. The mass effect of the lesion was observed to displace the trachea and adjacent perivertebral, dangerous, and retropharyngeal spaces anteriorly. An excisional biopsy was made with the diagnosis.

Inflammatory pseudotumors are a heterogeneous group of mesenchymal neoplasms, with the inflammatory myofibroblastic tumour (IMT) being the most common [1]. These types of lesión, which are generally associated with a history of trauma, infectious processes, and post-surgical events among the most frequent causes, have an unknown aetiology. Some of the proposed causes suggest a traumatic origin and surgical inflammation or an immune-autoimmune condition. Additionally, there have been reports of inflammatory pseudotumors associated with IgG4-related sclerosing disease [1,2-4]. Histologically, presents with a storiform (spiral-like) pattern of spindle-shaped fibroblasts or myofibroblasts in the fibrous stroma of the node with extension to lymphoid tissue and perinodal tissue. Vascular proliferation and mixed inflammatory infiltration of plasma cells, histiocytes, dendritic cells, neutrophils, and fibroblasts [3]. IMTs are more commonly found in the lungs and abdomen, with the most common age group being children and young adults [2]. Symptoms vary depending on the tumour's location and size. Tumours in the cervical region can cause mass effect primarily on adjacent structures, resulting in dyspnea and dysphagia. IMTs involve ALK (anaplastic lymphoma kinase) in 50% of cases [1]. Between 15% to 30% of patients display a cluster of symptoms known as "inflammatory syndrome", which includes fever, weight loss, and malaise. In these patients, laboratory tests may uncover various abnormalities, such as microcytic anaemia, elevated erythrocyte sedimentation rate, thrombocytosis, and/or polyclonal hypergammaglobulinemia [5].

IMTs are relatively infrequent in the bones compared to other locations. The imaging characteristics are not specific and most of the time it depends on the histopathological features. They can range from a poorly defined, infiltrating lesion to a well-circumscribed soft tissue mass, with varying proportions of inflammatory and fibrotic elements within the tumour [1-5]. Delayed enhancement on tomography is a characteristic feature in cases with fibrotic tissue, while calcified IMTs can be better visualized in the bone window. On magnetic resonance imaging, IMTs may appear as low signal intensity on T1- and T2-weighted images due to the presence of fibrosis, as well as restricted diffusion [4], but it mostly depends on the content of the tumour, lesions with haemorrhage or cystic components and inflammation may appear hyperintense on those sequences. Treatment and management of IMTs depend on the location, size, and the patient's symptoms.

Teaching Points

1. Inflammatory pseudotumors are a diverse group of mesenchymal neoplasms, with the inflammatory myofibroblastic tumour (IMT) being the most common.
2. When presented with suspicion of IMT search for history of trauma, infectious processes, and post-surgical events.
3. Symptoms of IMTs vary depending on the location and size of the tumour.
4. The imaging characteristics of IMTs are non-specific and depend on the underlying histopathological features.
5. On MRI, IMTs may appear as low signal intensity on T1- and T2-weighted images due to the presence of fibrosis 

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