[size=6]15 year old presents with back pain. Primary care physician obtains and MRI (image below). You send alpha-fetoprotein and beta-hCG both of which are normal. What is the best course of action for this child?

 

 

a surgical resection

 

b observation

 

c sclerotherapy

 

d physical therapy[/size]

A

correct answer

a surgical resection

 

This MRI shows a tailgut cyst. Features on the MRI suggesting a tailgut cyst include multicystic pattern with small cysts clustered around larger ones and a high signal intensity relative to muscle. The hyperintense signal is indicative of mucin.

 

Tailgut cysts are rare and are known to be more frequently seen in middle-aged women. These cysts are usually in a retrorectal location, but may be found in the subcutaneous region. Although this child’s back pain is likely unrelated to the MRI finding, surgical resection of this lesion is recommended. Surgical approach depends on the location and size of the lesion. Most commonly, a posterior approach with removal of the coccyx will

allow the best visualization for removal of the multiloculated cyst. Surgical resection is recommended as there are reported cases of mucinous adenocarcinoma or carcinoid arising in them.

 

The differential diagnosis of lesions in this area includes sacrococcygeal teratoma and rectal duplication. Teratomas may have similar imaging characteristics but they more often contain fat and other components. Rectal duplications often communicate with the rectal lumen and are often located anterior to the rectum. Final diagnosis is based on pathologic examination of the resected specimen.

 

The risk of cancer makes observation or sclerotherapy less appropriate management choices. Physical therapy may alleviate her symptoms if they do not resolve after resection of the lesion.