Local rib invasion in non-small cell lung cancer : a bad prognostic factor that owes a characteristic scintigraphic appearance in dual phase osseous scintigraphy

الملخص EN

Tumor invasion of the chest wall in non-small cell lung cancer is one of the designation of T 3 resulting in upstaging of the tumor to stage III-A.

This augurs a worse prognosis.

Bone scan is a sensitive technique to detect remote metastases and local rib erosion.

Purpose : the rational beyond this study is that the presence of local rib destruction or involvement in the vicinity of a pulmonary shadow is virtually diagnostic of primary carcinoma of the lung associated with local rib erosion.

Aim of this study is to detect characteristic scintigraphic appearance in dual phase osseous scintigra-phy in diagnosis of local rib erosion in non-small cell lung cancer.

Patients and Methods: Sixty patients with histo-pathologically proven bronchogenic carcinoma were included in the current study.

Thirty had C.T.

evidence of local rib erosion (Group I) and the remaining had no rib erosion (Group II).

All were subjected to dual phase osseous scintigraphy.

Images were interpreted for local rib erosion depending on specific criteria (presence of over-perfused mass in blood pool images / hyper-vascular overlying ribs in early images / abnormal tracer uptake pattern in the same ribs in late images).

A scoring system was created for each patient according to presence or absence of these criteria.

Results : Twenty-eight patients in group I had hyper-vascular soft tissue mass in blood pool images versus 23 in group II.

Over-perfused overlying ribs were seen in 28 patients in group I, in addition to rib involvement in late images in all patients in this group.

Single involvement of one rib related to but remote from the hyper-vascular mass was seen in group II that proved to be distant metastatic deposit.

Conclusion : dual phase osseous scintigraphy has characteristic scintigraphic criteria that can diagnose local rib erosion in non-small cell lung cancer with high sensitivity and specificity.

These criteria are : over-perfused soft tissue mass and overlying ribs in early blood pool images associated with abnormal tracer uptake in the same ribs in late images.

Proper diagnosis of local rib erosion has a great impact on prognosis and subsequent patient management particularly in absence of remote osseous metastases.