Final answer:
The second most common primary retroperitoneal malignancy is lymphoma. Differential diagnoses include pancreatic cancer, kidney cancer, and adrenal tumors.
Step-by-step explanation:
The second most common primary retroperitoneal malignancy is lymphoma. Differential diagnosis for retroperitoneal malignancies include pancreatic cancer, kidney cancer, and adrenal tumors. Retroperitoneal malignancies occur outside the peritoneal cavity, such as between the parietal peritoneum and the abdominal wall.
When considering a diagnosis, it is important to differentiate retroperitoneal malignancies from other cancers, which may include those of the gastrointestinal tract like colorectal cancer, urogenital tract such as bladder cancer or prostate cancer, and systemic cancers such as melanoma or Hodgkin lymphoma, which can also affect this anatomical region. Specialists must consider a variety of neoplasms when evaluating a patient with a suspected primary retroperitoneal malignancy.