Rationale and Objectives
Inguinal lymph nodes can be the first or the only clinical signs of tumor metastases. The aim of the study was to evaluate the role of contrast-enhanced high-resolution magnetic resonance (MR) lymphangiography in diagnosis of inguinal lymph node metastases.
Materials and Methods
The study enrolled 26 patients with inguinal lymph node metastases. Contrast-enhanced lymphangiography was performed using a 3.0T MR unit after intracutaneous injection of gadobenate dimeglumine into the interdigital webs of the dorsal foot. Images of inguinal lymph nodes were acquired before and after contrast injection.
Results
All patients exhibited edema in the subcutaneous layer with significant dilatation of lymphatic collectors in the affected lower limbs on MR images. Before contrast injection, the outline and structure of the affected nodes were unclear on T2 weighted images. Structural changes became evident on postinjection T1-weighted images. Nodal involvement on contrast enhanced MR lymphangiograms was characterized as: 1) heterogeneous structure with partial or marginal enhancement of the node indicating partial occupation by tumor; 2) homogeneous structure of the node without contrast enhancement, indicating total occupation with metastasis, with increase or no change in size; and 3) heterogeneous structure with punctiform nodal enhancement indicating diffuse growth of tumor within the node. Further examinations confirmed the diagnoses of inguinal lymph node metastases of either regional or distal tumors.
Conclusions
Contrast-enhanced high-resolution MR lymphangiography was a sensitive modality in the diagnosis of malignant peripheral lymphedema and the identification of inguinal lymph node metastasis in patients with various tumor origins.
Introduction
The spread of tumors to lymph nodes is an important means of tumor dissemination. Inguinal lymph node metastasis can be a manifestation of different tumor origins. Because of the impairment of lymph backflow within the tumor occupying inguinal metastasis often accompanied by malignant lymphedema of the affected lower limb. Malignant lymphedema could be the first or the only physical sign of tumor metastasis through the lymph nodal pathway and often confused with benign lymphedema, the latter occurs in the extremities because of congenital lymphatic system dysplasia, or acquired lymphatic damage caused by injury, infection, or surgical procedures. Therefore differential diagnosis of benign lymphedema and malignant lymphedema is of primary importance. A sensitive and reliable imaging modality to detect the involved lymph node will be favorable to an earlier diagnosis. Magnetic resonance imaging (MRI) is considered superior to computed tomography (CT) for local staging of carcinoma . Recently, high-resolution MRI with various contrast agents that are injected intravenously has emerged as a new diagnostic method in the clinic. This modality has much higher accuracy rates in detecting nodal metastasis than conventional MRI . High-resolution MR lymphangiography has been proven to be useful in the diagnosis of peripheral lymphatic system disorders in the author’s clinic as well as in other clinics . Based on MR lymphangiography findings in our clinic, 26 patients were diagnosed with inguinal lymph node metastasis and malignant lymphedema of the lower extremities. Further pathological and laboratory tests revealed that tumors that had spread to the inguinal lymph nodes had diverse origins. In all patients, swelling of the lower extremities and external genitalia was the first and/or the only clinical symptom of the disease. All of these patients had been misdiagnosed as benign lymphedema before they came to our clinic. Here, we present the MR lymphangiographic findings and clinical data of these patients.
Materials and methods
Patients
Twenty-six patients with swelling of the lower extremities and external genitalia were included in this study. Among the patients, 8 had bilateral and 18 had unilateral lymphedema. Nine patients also exhibited edema of the external genitalia and/or lower abdominal wall. An inguinal mass (enlarged inguinal lymph nodes) was found in 5 patients. The clinical characteristics of the patients are summarized in Table 1 . Eleven were female and 15 male. The mean age of patients was 55 (range 32–82) years. The mean duration of swelling was 9.75 months (range 1 week–2 years). Eight patients had previously undergone surgical treatment for malignant tumors with various origins.
Table 1
Characteristics of the 26 Patients in the Study
Characteristics Value Age (y) Mean 55 Range 32–82 Duration of disease Mean 9 month Range 1 week to 2 years Inguinal mass 5 Edema in subcutaneous 26 Edema in both subcutaneous and muscle 7 Regional Scrotum Paget’s disease 2 Bladder cancer 1 Prostate cancer 2 Cervical cancer 4 Ovarian cancer 2 Nonregional Liver cancer 1 Non-Hodgkin lymphoma 2 Colon cancer 3 Nasopharynx cancer 1 Gastric cancer 1 Atypical fibrohistiocytoma 1 Gastrointestinal adenocarcinoma of unknown origin 2 Retroperitoneal fibrosis 1 Malignant metastasis of unknown origin 2
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MR Lymphangiography Test
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Results
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Table 2
Magnetic Resonance Lymphangiographic Findings of Nodal Metastasis in 26 Patients
Inguinal Node Involvement Iliac Node Involvement Superior Group Median (Deep) Group Inferior Group Type of nodal changes Irregular in shape 6 (case) 6 6 No enhancement 16 15 7 1 Partial enhancement 6 7 11 Marginal enhancement 2 Punctiform enhancement 2 2 3 4 Full enhancement 2 2 3 1 Enlargement of affected node 18 18 18 No change in size of affected node 8 8 8
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Discussion
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