DF derived from rib is extremely rare and occurs at any age without gender difference. Local pain and swelling are the most common symptoms in DF patients. Up till today, only 7 cases have been published in the English literature[4–8]. Table 1 summarizes all these cases including the present case. The most common clinical symptoms are local chest pain and swelling, and the major imaging features are osteolytic change and cortical bone destruction, as well as invasion into surrounding soft tissues. Pathological fracture, it should be noted, may occur in some cases. Cystic change was found in just two cases. Moreover, total excision and chest wall reconstruction were performed in three cases. However, recurrence occurred in two cases treated with curettage.
Table 1
Summarization of reported cases of desmoplastic fibroma in rib
Author
|
Age
|
Sex
|
Clinical symtoms
|
Location
|
Size(cm)
|
Radiographic findings
|
Treatment
|
Follow-up
|
Butters et al.[1]
|
17
|
M
|
Pain and swelling
|
Left 6th
|
-
|
Osteolytic and non-destruction
|
Resection
|
-
|
Taconis et al.[2]
|
57
|
F
|
Swelling
|
Right 5th
|
-
|
Osteolytic, destruction and soft tissue extension
|
Curettage
|
Recurence after 9 year/9 year
|
Barbashina et al.[3]
|
19
|
M
|
Swelling
|
Left 10th
|
11.0
|
Osteolytic and destruction
|
Total resection
|
-
|
Kaddour et al.[4]
|
45
|
M
|
Pain and hypoesthesia
|
Right 2nd
|
7.0
|
Expensive formation
|
Resection
|
NER/4 year
|
Kaddour et al.[4]
|
55
|
F
|
Swelling
|
Right 8th or 9th
|
10.0
|
Osteolytic and soft tissue extension
|
Wide resection
|
Recurence after 2 year/2 year
|
Taketo Okubo[5]
|
40
|
M
|
Swelling
|
Right 9th
|
14.0
|
Cystic and destruction
|
Total resection
|
NER/6 months
|
Present case
|
35
|
M
|
Pain and swelling
|
Left 6th
|
4.2
|
Cystic and destruction
|
Total resection
|
NER/22 months
|
CT and MRI scan are generally applyed to evaluate the invasion degree of tumor for the next planning operation. The rarity and non-specific radiographic findings of DF sometimes make radiological diagnosis rather difficult, because the similar imaging features may be found in other bone lesions such as extra-abdominal desmoid tumor invading bone, eosinophilic granuloma and low-grade osteosarcoma. Radiological findings could confirm whether the tumor is originating from rib or not. In this case, enhanced CT scan showed low-density area with 6th rib destruction, and it revealed that the tumor was aggressive. Moreover, the pathological differential diagnosis is obviously a challenging work, which means that pathologists have to exclude other benign or low-grade malignant bone tumors such as FD, low-grade intraosseous osteosarcoma and low-grade fibrosarcoma[9]. In view of the difficulty in differential diagnosis, making a correct diagnosis is rather essential. Furthermore, immunohistochemical of β-catenin are important for differential diagnosis, since the APC/β-catenin pathway has been proved to be associated with desmoid-type fibromatosis. Several studies showed that β-catenin plays a vital role in the tumorigenesis of desmoid tumors other than DF[10, 11]. In the present case, IHC of β-catenin is negative, thus further certifying the diagnosis of DF.
The rate of recurrence in DF dealt with local curettage or intralesional resection is almost 40%[1, 12]. Due to the risk of tumor recurrence, the optimal treatment for DF is wide or total resection with partial normal tissue arround the tumor. However, there is no uniform treatment guideline for DF currently. Local irradiation is not routinely recommended because of its side-effects. If there was a huge defect in chest wall after surgery, repairment with the tissue-engineered ribs should take into consideration[13]. Postoperative recurrence may occur in those who just underwent curettage or wide resection especially in those large tumors[5, 7]. Therefore, it is a crucial step to choose the surgical approach. Total resection may reduce the rate of local recurrence but increase the chest surgical trauma and bring patients unsatisfactory chest-wall appearance. Considering that the rib tumor was relatively small, we finally performed wide resection rather than total resection. In addition, another opinion about the tumorous type is that DF is a kind of “border-line” tumor rather than benign tumor[1, 12]. Metastases have never been reported. In my opinion, this view can more accurately describe the biological behavior of the tumor. Fortunately, this case successfully received wide excision with no evidence of recurrence 22 months after surgery.
In summary, this case demonstrates aggressive characteristic of desmoplastic fibroma despite its benign nature and rarity. If the rib mass is relatively small and difficult to exclude malignancy, wide excision should be performed to reduce the rate of recurrence.