Potential role of BCL2 in the recurrence of uterine smooth muscle tumors of uncertain malignant potential

Abstract

Uterine smooth muscle tumors are the most common female genital tract neoplasms. While leiomyosarcoma has been studied at length, smooth muscle tumors of uncertain malignant potential (STUMPs) still have ambiguous and unresolved issues, with a risk of relapse and evolution largely undefined. We performed an array comparative genomic hybridization analysis on a primitive STUMP and its local recurrence, histologically diagnosed as undifferentiated sarcoma. To the best of our knowledge, our report is the first genomic study on primitive STUMPs and the different relapsed tumors. The results showed few copy number alterations shared between both samples and the high heterogeneity in the STUMP was apparently lost in the sarcoma. Surprisingly the STUMP presented an amplification of the BCL2 gene, not observed in the relapsed tumor. Additionally, fluorescence in situ hybridization and immunohistochemical staining were performed to confirm BCL2 amplification and expression in these samples and in two other cases of primitive STUMPs and their corresponding relapsed tumors. The presence of BCL2 in multiple copies and expression in the two primitive STUMPs and two relapsed tumors was confirmed. The marked amplification of the BCL2 gene present in the primitive STUMP and the multiple copies also observed in other cases, suggest its potential role as a marker of STUMP malignant potential and recurrence.

Figure 1.

Evaluation system for the BCL2 protein.

Figure 2.

(A) Genomic profiles of both a STUMP and the undifferentiated sarcoma. (B) Chromosome 18 with BCL2 amplification in STUMP (left) and the absence of gain in the undifferentiated sarcoma (right). STUMP, smooth muscle tumors of uncertain malignant potential.

Figure 3.

(A) Nuclei after FISH with an IGH/BCL2 probe in primitive STUMP. (B) Nuclei after FISH with an IGH/BCL2 probe in relapsed sarcoma. (C) Distribution of BCL2 and IGH signals in primitive STUMP. (D) Distribution of BCL2 and IGH signals in relapsed sarcoma. (E) Distribution of BCL2 and CEP18 probe signals in undifferentiated sarcoma (left) and nuclei with polysomy of chromosome 18 (right). (F) Distribution of BCL2 and CEP18 probe signals in case 2. (G) Distribution of BCL2 and CEP18 probe signals in case 3. (H) Distribution of UroVysion probe signals on primitive STUMP. STUMP, smooth muscle tumors of uncertain malignant potential.

Figure 4.

(A) Hematoxylin and eosin staining of a primitive STUMP. (B) Hematoxylin and eosin staining of a relapsed sarcoma. (C) Bcl-2 immunohistochemical staining of a primitive STUMP. (D) Bcl-2 immunohistochemical staining of a relapsed sarcoma. STUMP, smooth muscle tumors of uncertain malignant potential.

Figure 5.

Schematic representation of the endoreduplication hypothesis.