Endobronchial Lipoma – Clinicopathologic Analysis of 12 Cases Showing Benign Behavior and Lack of 12q13-15 Amplification, Despite Worrisome Morphological Features
Jennifer M Boland, Karen J Fritchie, Michele R Erickson-Johnson, Andre M Oliveira, Thomas V Colby, Andrew L Folpe. Mayo Clinic, Rochester, MN; Mayo Clinic, Scottsdale, AZ
Background: While lipomatous neoplasms are common in soft tissue locations, they rarely involve the bronchial tree. In our experience, lipomatous tumors of the bronchial tree often contain enlarged, atypical-appearing stromal cells, raising the possibility of well-differentiated liposarcoma. The clinicopathological and molecular cytogenetic features of endobronchial lipomatous tumors have not been previously studied in detail.
Design: Cases were obtained by searching the consultation archives of the authors (ALF and TVC), and the surgical pathology archives of Mayo Clinic Rochester for cases coded as “lipoma”, “lipomatous hamartoma” and “liposarcoma” involving the bronchus or lung. All cases were reviewed by two soft tissue pathologists (ALF and KJF). Clinical information was obtained from clinical records and referring clinicians, where applicable. Selected cases were studied with FISH for CPM, HMGA1 and HMGA2.
Results: The tumors occurred predominately in men (91%), and patient age ranged from 44-80 years (mean 65 years). Most patients (80%) had a former or current history of heavy smoking (20-100 pack-years). Three patients had concurrent pulmonary squamous cell carcinoma, and one had a previous history of multiple lung cancers. Most lesions were discovered incidentally. The endobronchial lipomatous neoplasms showed areas of fibrosis containing scattered hyperchromatic stromal cells, suggestive of well-differentiated liposarcoma. However, all such cases failed to show amplification of CPM/MDM2, typical of well-differentiated liposarcoma, and all patients were either alive without evidence of disease or had died of other causes at last follow-up. Additionally, of seven cases tested for HMGA1 and HMGA2 rearrangement, four had rearrangement of HMGA2 and one had rearrangement of HMGA1, consistent with the expected profile observed for ordinary lipomas.
Conclusions: Although the morphological features of endobronchial lipomatous neoplasms may suggest the possibility of well-differentiated liposarcoma, our clinical and molecular cytogenetic findings strongly suggest that these represent lipomas instead. Given the clinical importance of distinguishing benign from malignant adipocytic lesions in these anatomical locations, we recommend liberal use of ancillary molecular cytogenetic tests for the evaluation of problematic cases.
Category: Bone & Soft Tissue
Tuesday, March 5, 2013 1:00 PM
Poster Session IV # 23, Tuesday Afternoon