Monday, June 29, 2015

Pheo spillage?

Although I am not a surgeon, I am often asked by patients about surgical approaches. One of the common questions is how laparoscopic pheo resection can completely remove the tumor. The ports look small; how can a tumor 5-cm large pass through the ports? Even if the tumor can squeeze through the ports, will that cause fragmentation of the tumor or cause tumor spillage?  I usually ask the patients to direct the questions to the surgeons but I do wonder if tumor spillage can actually happen.

Then I saw a case report published this year. It described a 64-year-old woman with a large (12-cm) pheo. The pheo was resected laparoscopically. The tumor was completely removed but the tumor capsule ruptured. Tumor histology showed relatively high cell division rate but otherwise there was no suggestion that the tumor was malignant. Several months later, the pheo recurred at the primary site and the abdominal wall where the laparoscopic ports were. The tumor progressed quickly and the patient unfortunately died of it.  

The references cited in the case report listed an older study published in 2001. Three patients with single pheos 5.5-6.5-cm large had small multiple recurrent pheos at the same site of the original pheos 3-4 years after laparoscopic resection. In all three cases, tumor spillage was suspected by the surgeons. No abdominal wall seeding was found in the 3 cases.

In retrospect, the case reported this year probably had malignant pheo while the 3 earlier cases probably had benign pheo. At any rate, pheo spillage indeed appears possible during laparoscopic resection but should be very uncommon.

Dr. Pheo

Monday, February 2, 2015

A non-genetic risk factor for pheo?

Patients with pheo often ask “why do I have pheo?” I usually assure them that nothing we know of, other than genetic risks, causes pheo. There is no clear evidence that common risk factors such as smoking, obesity, diet, infection, and exposure to environmental toxins are associated with higher pheo risk. There is also no clear evidence that other diseases the patient has, other than those that are part of a genetic syndrome, are associated with higher pheo risk.

An interesting paper published online last month seems to suggest that cyanotic congenital heart diseases may predispose people to develop pheo. The idea that hypoxia may lead to pheo is not too new now. About half of the genes that cause pheos when mutated are involved in making molecules carrying energy. As making energy molecules requires oxygen, the mutated genes mislead the cell into thinking that it lacks oxygen supply (hypoxia). The cellular processes that try to cope with hypoxia, over time, can result in pheos. It has been reported that people living in high altitude (thus low oxygen levels) tend to have more neck paras and perhaps pheos. The new paper now shows that people with cyanotic congenital heart disease may also tend to have more pheos.

Cyanotic congenital heart disease is a congenital condition in which the abnormal heart structure causes mixing of blood from the two sides of heart, thus low oxygen levels in the artery and tissue. The new paper shows that people with cyanotic congenital heart disease have a 6-fold risk of having a pheo diagnosis, compared with those without, during their hospitalization for whatever causes. In the same paper, the authors also identified 20 patients with congenital heart disease and pheo, 18 of them having cyanotic disease, 2 having aortic coarctation. The 18 patients with cyanotic congenital heart disease were younger than the average patients with pheo and tend to have multiple tumors. Unfortunately, the paper does not specify the 18 patients were out of how many patients with cyanotic congenital heart disease so that we don’t know the incidence of pheo in those patients.

As the authors prudently cautioned, their study only establishes an association between pheo and cyanotic congenital heart disease but not a causal effect of chronic cyanosis. One other potential bias is from ascertainment. If more patients with cyanotic congenital heart disease are tested for pheo, more pheos will be diagnosed. Nonetheless, I will ask my next patient with suspected pheo whether she/he has a history of congenital heart disease, especially a cyanotic one.  


Dr. Pheo