Possible Differentiation Between Recurrent Lymph Nodes of Bladder Cancer and Malignant Lymphoma on Ultrasound: A Case Report

In clinical practice, diagnostic physicians often have difficulty distinguishing between malignant lymphomas and recurrent lymph nodes of prior solid malignancies. An 86-year-old man, with a past history of bladder cancer, complained of pain around the left shoulder. Ultrasound showed multiple round masses extending from the left neck to the left axilla, with mixed high and low internal echoes and enhanced posterior echoes. Positron emission tomography showed avid fluorodeoxyglucose uptake, i.e., a maximal standard uptake value (SUV max) of 19. Magnetic resonance imaging of the (peri)axillary nodes showed low signals on T1-weighted images and predominantly very weak high signals on fat-suppressed T2-weighted images. Blood tests showed an elevated squamous cell carcinoma (SCC) antigen level of 9.5 ng/mL and a mildly elevated soluble interleukin-2 receptor (sIL-2R) level of 851 U/mL. Ultrasound findings highly suggested the recurrence of bladder cancer but could not rule out possible malignant lymphoma due to the elevated sIL-2R level. We, therefore, performed an excisional biopsy of the enlarged but easily resectable lymph node in the axilla. Frozen section of the target lesion showed no lymphoma cells but atypical cells proliferating in a solid fashion, with keratinization, intercellular bridges, and hypo-cellular areas. Immunostaining showed GATA3, p40, and CK5/6 positivities, leading to the diagnosis of SCC metastasis to the lymph node. Due to both the patient's old age and preference, he did not receive chemotherapy and only underwent radiotherapy to the supra-clavicular, axillary, and intra-abdominal foci for disease control, unfortunately resulting in the discontinuation of radiotherapy shortly thereafter due to severe side effects, including grade 2 diarrhea. The patient, therefore, has been receiving best supportive care for three months after the excisional biopsy. Diagnostic physicians should note that malignant lymphomas rarely have internal high echoes.