Sarcoma of unknown primary: myth or reality?

BACKGROUND: Sarcoma of unknown primary (SUP) designates an enigmatic entity with histologic confirmation of a metastatic tumor without an identifiable primary after a thorough diagnostic workup. The term "unknown primary" is heavily debatable given that sarcomas can arise from any tissue that harbors its histological structure. In this review, we discuss the validity of SUP as a distinct entity. Medline/PubMed and Google Scholar were searched from 1990 until April 2020 for publications in the English language reporting on SUP. We excluded articles reporting on cases with sarcomas from known organ sites such as lung or uterine sarcomas as well as synovial sarcomas. The Kaplan-Meier method was used to compute the median overall survival. A total of 26 patients with SUP were identified. The median age at diagnosis was 17.5 years with a similar prevalence among men and women. The tumors most commonly reported were alveolar rhabdomyosarcoma and rhabdomyosarcoma not otherwise specified. Almost two-thirds of the patients were reported to have more than one metastatic site. Among the 13 patients with survival data, the median overall survival was 10.0 months. Two patients underwent autopsy and had their primary culprit identified in the chest wall and paravertebral. CONCLUSIONS: This review showed that SUP shares with sarcomas of known primary similar clinical features including an aggressive clinical course, generally poor response to chemotherapy, and dismal patient outcomes. Thus, SUP does not appear to display a different natural history and biological properties that would allude to a distinct entity.

ALK gene rearrangement status in non-squamous non-small cell lung carcinoma in the Middle Eastern population.

BACKGROUND: Worldwide, the frequency of ALK rearrangement ranges between 3-6%, however its prevalence in the Middle Eastern population has not been reported. The aim of this study is to determine the frequency of the ALK rearrangement, as well as the clinico-pathologic characteristics of Lebanese patients with ALK-rearranged lung adenocarcinoma. METHODS: 152 patients diagnosed with non-squamous non-small cell lung carcinomas (NSCLC), at Hôtel-Dieu de France University Hospital between February 2014 and July 2016, were included in the study. ALK gene rearrangement expression was screened by immunohistochemistry (IHC) (D5F3 Clone). Positive cases were then sent for confirmation with Fluorescence in situ hybridization (FISH) technique. RESULTS: On immunohistochemistry, patients were distributed as following: score 0: n=108, score 1+: n=26, score 2+: n= 9, score 3+: n= 9. ALK gene rearrangement was detected in 6 out of 18 (2+ and 3+ score) tested patients by FISH technique. The presence of ALK rearrangement was significantly associated with the female gender (n=6, p=0.003) and with non-smoking status (n=4, p=0.0.18). CONCLUSION: This study confirms that the prevalence of the ALK gene rearrangement in the Middle Eastern region is within the worldwide ranges and is almost exclusive to patients with adenocarcinoma subtype and tends to occur more frequently in women and non-smokers.