A computed tomography (CT) scan of the neck is a common imaging tool for evaluating masses and enlarged lymph nodes. When lymphoma is suspected, understanding its appearance on a CT scan is important. This article describes the characteristic findings and common locations of lymphoma on a neck CT.
Understanding Neck CT Scans for Lymphoma
A CT scan provides detailed cross-sectional images of the neck, useful for visualizing lymph nodes and soft tissues. Patients undergoing a neck CT for suspected lymphoma often receive intravenous (IV) contrast material. This contrast helps highlight blood vessels and abnormal tissues, making it easier to identify and characterize masses or enlarged lymph nodes.
CT images allow medical professionals to assess the size, shape, and internal structure of lymph nodes. This helps determine if nodes are suspicious for lymphoma and aids in treatment planning by showing their relationship to surrounding structures.
Key Features of Lymphoma on CT
Lymphoma often presents with specific features on a neck CT scan, though variations can occur depending on the lymphoma subtype. Enlarged lymph nodes are a key indicator, typically measuring over 1.0 to 1.5 centimeters in their shortest dimension and appearing oval or round.
On non-contrast CT scans, lymphomatous nodes are commonly homogeneous, with a uniform density similar to muscle tissue. After contrast, these nodes usually show mild to moderate, uniform enhancement. This consistent pattern helps distinguish lymphoma from other conditions with more varied or irregular enhancement.
A common finding in lymphoma is the absence of central necrosis or cystic degeneration within enlarged lymph nodes. Unlike many inflammatory or metastatic nodes, which often show areas of breakdown or fluid-filled spaces, untreated lymphoma nodes are less likely to exhibit these features. Calcification within lymph nodes is also rare in untreated lymphoma. However, some aggressive lymphoma subtypes, such as peripheral T-cell lymphoma or high-grade non-Hodgkin lymphoma, can display heterogeneous enhancement or necrosis.
Lymphoma can also involve tissues outside lymph nodes, known as extranodal involvement. This is more common in non-Hodgkin lymphoma, occurring in about 40% of cases, compared to Hodgkin lymphoma, where it is seen in approximately 5% of cases. In the neck, extranodal lymphoma may appear as a mass or infiltrative lesion in structures like the salivary glands, thyroid gland, or muscles.
Common Locations in the Neck
Lymphoma can affect various neck regions, often involving specific lymph node chains. The cervical lymph nodes are frequently affected, including groups such as the submental and submandibular nodes (Level I), the upper, mid, and lower jugular nodes (Levels II, III, IV), and the posterior triangle nodes (Level V).
The deep lymphatic chains, particularly the internal jugular chain, are common sites for lymphoma. It can involve single or multiple node groups, sometimes appearing as matted masses where several enlarged nodes fuse. Extranodal involvement in the neck can occur in areas like Waldeyer’s ring, the paranasal sinuses, and the nasal cavity.
Differentiating Lymphoma from Other Neck Masses
Radiologists evaluate CT findings to distinguish lymphoma from other neck masses. While lymphoma has characteristic imaging features, other common causes of enlarged neck nodes, such as infections or metastatic cancer, can present similarly. For example, reactive lymphadenopathy from infection or metastatic carcinoma can cause enlarged nodes.
Certain CT findings may suggest conditions other than lymphoma. Significant central necrosis, extensive calcification, or irregular margins within a lymph node can indicate metastatic carcinoma or inflammatory processes. Highly irregular or marked heterogeneous enhancement may also be less typical for classic lymphoma. However, aggressive lymphoma subtypes can exhibit some atypical features, making definitive differentiation based solely on imaging challenging.
What Happens After Suspicious Findings
If a neck CT scan reveals findings suspicious for lymphoma, further diagnostic steps follow. Imaging alone cannot provide a definitive diagnosis; a tissue sample is required for microscopic examination. The most common next step is a biopsy, which can be an excisional biopsy (removal of the entire node) or a core needle biopsy (removal of a small tissue sample).
A biopsy allows pathologists to analyze cells, confirm lymphoma, and determine its specific type. Once lymphoma is confirmed, additional tests like a positron emission tomography (PET) scan, often combined with CT (PET/CT), may be used. These scans help determine the extent of the disease throughout the body, a process known as staging, which guides subsequent treatment decisions.