Peritoneal "melanosis".

Area of Science:

• Gastroenterology
• Pathology
• Surgical Oncology

Background:

• Peritoneal melanosis is a rare condition characterized by melanin deposition in the peritoneum.
• It is often associated with gastrointestinal malignancies, particularly colorectal cancer.
• Distinguishing peritoneal melanosis from metastatic melanoma is crucial for appropriate patient management.

Observation:

• A case of a 23-year-old female with adenocarcinoma of the rectum presented with diffuse black pigmentations.
• These pigmentations were observed on the parietal peritoneum, greater omentum, mesenteric lymph nodes, and ovaries during laparoscopic surgery.
• Histopathological examination revealed macrophages laden with black pigment.

Findings:

• The clinical and histopathological findings excluded metastatic melanoma.
• The diagnosis of peritoneal melanosis was confirmed.
• This represents the second reported case of peritoneal melanosis associated with adenocarcinoma of the large intestine.

Implications:

• Laparoscopic treatment was continued due to the benign nature of the observed lesions.
• This case highlights the importance of accurate diagnosis in differentiating peritoneal melanosis from metastatic disease.
• Further research may elucidate the exact pathogenesis and optimal management strategies for peritoneal melanosis.