In the case of a 65-year-old male presenting with fatigue and abdominal girth, which condition is most indicative of peritoneal metastatic disease?

A firm, red nontender nodule at the umbilicus, known as Sister Mary Joseph nodule, is a classic sign of peritoneal metastatic disease. This nodule arises due to metastases from intra-abdominal malignancies, particularly cancers of the gastrointestinal tract, and represents a manifestation of spread to the peritoneum or adjacent organs. The presence of such a nodule is particularly noteworthy in the context of a patient presenting with fatigue and increasing abdominal girth, as it implies underlying malignancy and peritoneal involvement.

The other options, while they may suggest other underlying conditions, do not specifically indicate peritoneal metastasis. Spider angiomata can occur in liver disease but are not exclusively indicative of malignancy or peritoneal involvement. Acute abdominal pain may suggest various acute abdominal conditions but lacks the specificity to metastatic disease. High blood pressure readings could indicate several issues unrelated to peritoneal metastasis, such as cardiovascular disease or other systemic illnesses.