[1797] Temporal Evolution of Histologic and Cell-Kinetic Parameters of Recurrent and Metastatic Thymic Neoplasms.

Anja C Roden, Eunhee S Yi, Janis L Donovan, Stephen D Cassivi, Yolanda I Garces, Randolph S Marks, Marie Christine Aubry. Mayo Clinic, Rochester

Background: Thymic neoplasms are generally considered as low grade malignancies, which can recur or metastasize. The temporal evolution of histologic and cell-kinetic features in recurring and metastasizing thymic neoplasms has not been studied.
Design: Medical records from 15 patients (pts) (0.05%) treated for thymic neoplasm, 1970-2006, who developed recurrence (recur) and/or metastasis (met) were reviewed. Two pathologists classified all cases (WHO) with consensus diagnosis. Ki-67 LI was expressed as %pos/100 epithelial cell (EC) nuclei (mean of 1000 EC counted over 3 areas) and mitotic activity (MA) as mitoses/10Hpf (mean of 50Hpf counted).
Results: 10 men & 5 women with a median age of 50.3 yrs underwent complete resection of the original tumor (OT) (n=14), or had a biopsy (n=1). 7 pts had additional therapy. Masaoka stages were I (n=2), II (n=6), III (n=5), IV (n=2). OTs were classified as WHO types A (n=1, 6.7%), B1 (n=2, 13.3%), B2 (n=7, 46.7%), B3 (n=2, 13.3%), thymic carcinoma (n=2, 13.3%), atypical thymic carcinoid (n=1, 6.7%). For comparison, all thymic neoplasms treated during that time were classified as A (10.9%), AB (16.1%), B1 (22.3%), B2 (27.4%), B3 (12.4%), thymic carcinoma (7.3%), others (3.6%). Pts had 1 (n=5), 2 (n=4), or 3 (n=2) recurrences. 13 pts had mets, 8 of which also had recurrence(s). The mean interval between initial therapy and 1st recur/met was 6.0 yrs (range, 0 – 14.2 yrs). 30 resection specimens and 7 biopsies were evaluated for histology, Ki67 LI (n=33), and MA (n=31). In 5 cases, WHO type of the recur/met was different from the OT (Table 1).

Temporal evolution of histopathology
 Original tumor (OT)1st recur/met2nd recur/met3rd recur/met
CaseWHO (yrs after OT)   
2B2B2 (2.5)B3 (5.7)Thymic carcinoma (13.4)
3B2B3 (6.0)  
8B1B2 (5.6)  
9B2B2 (4.4)B3 (10.2) 
11B2B1 (8.8)  

Median Ki67 level and MA increased > 20% in 4 (of 13) and 6 (of 13) 1st recur/met and 1 (of 5) and 4 (of 4) 2nd recur/met specimens when compared to OT and 1st recur/met, respectively. F/u was available in all pts with a mean f/u time of 13.3 yrs (range, 0.6 – 18.9 yrs). 10 pts died, 4 of disease.
Conclusions: The histologic type in most recur/met thymic neoplasms remains unchanged from the OT and the proportion of type B2 and thymic carcinoma is higher when compared to all thymic tumors. Occasionally, B2 thymoma can recur/metastasize as a B3 or thymic carcinoma. Cell-kinetic parameters increase only in the minority of recur/mets. The relative low rate of progression in tumor type and in cell-kinetic parameters from OT to recur/met may explain the bland behavior of most thymic neoplasms.
Category: Pulmonary

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 255, Wednesday Morning


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