Cytogenetic subtype involving chromosome 13 in lipoma

Cytogenetic Subtype Involving Chromosome 13 in Lipoma Report of Three Cases Chandrika Sreekantaiah, Carol S. Berger, Constantine P. Karakousis, Uma Rao, Stanley P. L. Leong, and Avery A. Sandberg

ABSTRACT: We report three lipomas with rearrangements of chromosome 13. The karyotype of the

tumors studied were 45,XX,-8,+der(8)t(8;13)(q22;q12),del(10)(p12),-13; 46,XY, del(13) (q12q22), and 46,XY, t(11;12)(q23;q13),del(13)(q12q22), respectively, revealing common involvement of band 13q12 in the rearrangement. Three other lipomas with aberrations of bands 13q12-q13 have been reported, suggesting that such tumors with abnormalities of chromosome 13 could represent a subgroup of lipoma in addition to those already reported with abnormalities of chromosomes 12q and 6p. The rearrangements of #13 in all these cases also involved loss of the band 13q14 to which the antioncogene associated with retinoblastoma and osteosarcoma is localized. Detailed clinical, histopathologic, and molecular studies should help to further characterize the various cytogenetically defined subgroups of lipoma.

INTRODUCTION Lipomas are benign neoplasms of adipose tissue and constitute the most c o m m o n soft tissue tumors, benign or malignant, in h u m a n s [1]. Cytogenetic analyses of these neoplasms have demonstrated consistent involvement of bands 12q13-14 in over 70% of the cases studied [2, 3]. Recently, three lipomas with n o n r a n d o m aberrations in the 6p22-23 region were described [4]. We report three cases with abnormalities of chromosome 13, all involving band q12. In two cases the abnormality was an identical interstitial deletion, del(13)(q12q22), and the third involved a translocation with chromosome 8. Three other lipomas with rearrangement of 13q12-q13 have been reported i n the literature, one an interstitial deletion, del(13)(q13q31) [3], one a terminal deletion, del(13)(q12) [3], and the third an inv(13)(q12q31) [5]. The situation in lipomas thus appears analogous to that of leukemias and other tumors where a specific cytogenetic abnormality is k n o w n to characterize a particular subtype.

From The CancerCenter of Southwest BiomedicalResearch Institute,Scottsdale, Arizona(C. S., C. S. B., A. A. S.), RoswellPark MemorialInstitute,Buffalo,New York (C. K., U. R.), and the ArizonaCancer Center and Department of Surgery, Universityof Arizona,Tucson,Arizona(S. L.). Address reprint requests to: Avery A. Sandberg, M.D., The Genetics Center, 6401 E, Thomas Road, Scottsdale, AZ 85251. Received February 6, 1989; accepted March 14, 1989,

281 © 1989 Elsevier SciencePublishingCo., Inc. 655 Avenueof the Americas,New York, NY 10010

Cancer Genet Cytogenet39:281-288 (1989) 0165-4608/89/$03.50

282

c Sreekantaiah et al.

CASE REPORTS

Case 1

A 68-year-old w o m a n was referred for a lump on the right shoulder that had been present a p p a r e n t l y for 5 years. The patient reported a gradual increase in size of the lump. Physical examination showed a freely mobile, subcutaneous nodule in the area of the right s h o u l d e r measuring about 3.5 cm in diameter. The patient's daughter had been treated for angiosarcoma. On excision, pathologic examination revealed a lobulated 2.9 × 2.1 x 5 cm portion of fat tissue with an adherent, somewhat membranous, greyish-white soft tissue. Microscopically, the sections showed adipose tissue characterized by m o n o t o n o u s fat cells with no atypia. A thin fibrous capsule was present. Presently, the patient has a nodular density in the right lung that has grown since a chest x-ray in 1985. The patient u n d e r w e n t a fiberoptic bronchoscopy. Cytologic e x a m i n a t i o n of the bronchial washing and brush biopsies were negative for malignant cells. The patient refuses surgery/needle biopsy. Chest x-ray in July 1988 showed no change from June 1988. The patient is to be followed by chest x-ray every 3 - 4 months.

Case 2

A 55-year-old white male u n d e r w e n t wide excision of an in situ malignant melan o m a in the left mid-back in November 1986. He has been followed up to date w i t h o u t evidence of recurrence. However, he has developed several small melanotic lesions that have all been benign. A biopsy of a chest-wall nevus was diagnosed as dysplastic c o m p o u n d nevus. The patient is doing well. A l i p o m a of the left u p p e r arm was excised in June 1988. Pathologic e x a m i n a t i o n s h o w e d a fragment of fibroadipose tissue measuring 7 x 4.5 × 3 cm. Multiple crosssections revealed some foci of lobulated tissue, the largest measuring a p p r o x i m a t e l y 1 cm in diameter. On microscopic examination, the section showed lobulated fat c o m p o s e d of mature adipocytes lacking atypia and having a thin fibrous capsule.

Case 3

A 51-year-old white male came in for evaluation of a fairly large l i p o m a in the right lower back. The lipoma, w h i c h measured a p p r o x i m a t e l y 7 × 9 cm, had been present for at least 8 years. The patient reported an increase in size of the l i p o m a and that it was bothersome to him. It was excised under local anesthesia. On excision, pathologic examination of the s p e c i m e n revealed a circumscribed, solid, soft lipomatous-like tumor, measuring 7.5 x 5 × 3.5 cm. A diagnosis of benign l i p o m a with no evidence of malignancy was made.

MATERIALS A N D METHODS

T u m o r s p e c i m e n s collected in sterile transport m e d i a were processed and harvested according to the p r o c e d u r e described by Limon et al. [6]. In brief, this involved prolonged collagenase disaggregation and culture in RPMI-1640 m e d i u m supplem e n t e d w i t h 17% fetal bovine serum, 1% glutamine, and 2% antibiotics. After harvest, w h i c h was i n d i v i d u a l i z e d for each flask, air-dried slides were p r e p a r e d and G b a n d e d by the GTG m e t h o d [7].

283

Chromosome 13 Subtype in Lipomas

From the collagenase disaggregated cells, simultaneous coverslip cultures were also initiated according to the method of Peakman et al. [8] for amniotic fluid cell cultures. In brief, 0.5 ml of the suspension was pipetted onto a 22-mm 2 coverslip in a 35-mm Falcon plastic tissue-culture dish and incubated at 37°C in a 5% CO2 incubator. Care was taken to confine the drop to the coverslip, After 24 hours, 1.5 ml of medium was added to each dish. The unattached cells were removed, 2 ml of fresh medium was added, and the dishes were reincubated. The dishes were checked microscopically every day for mitoses. The harvest procedure included exposure to colcemid for 2 hours, hypotonic treatment (0.8% sodium citrate) for 20 minutes at room temperature, and fixation in 3 : 1 methanol : acetic acid fixative (v/v). For fixation, 2 ml of freshly prepared fixative was added gradually along the sides of the dish to the hypotonic solution and left undisturbed for 2 minutes. The fixative, freshly prepared each time, was then changed three times after 20, 20, and 10 minutes, respectively. The coverslips were air dried using airflow from an aquarium pump, placed overnight on a warming tray at 50°C, and G banded [7]. The karyotypes were expressed according to the ISCN [9]. CYTOGENETIC RESULTS Case 1

The cells were cultured for 7 days. Fifteen G-banded metaphases were analyzed and showed the following karyotype in all cells: 45,XX,-8,+der(8)t(8;13) (q22;q12),del(10)(p12),-13 (Fig. 1).

1 Representative G-banded karyotype from case 1: 45,XX,-8,+der(8)t(8;13) (q22;q12),del(10)(p12),- 13.

Figure

!-t 1

2

o

T

4

5

11

12

16

17

18

21

22

3

I-Y

!---j-

.

13

14 .

19

10

.

.

15

.

.

.

.

.

20

Y X

284

C. Sreekantaiah et al.

1

2

3

6

7

8

13

,-

tlt1-'

14

.... 19

Figure 2

1t 20

15

g--t

9

4

5

10

11

12

16

17

18

I--

I - - A . O~- . 21

. . .

22

~

Y

G-banded karyotype of a metaphase from case 2 with the del(13)lq12q22).

Case 2

T w e n t y - t w o G-banded metaphases obtained from cells cultured for 6 days were a n a l y z e d and all showed an interstitial deletion of chromosome 13, del(13)(q12q22), as the only a b n o r m a l i t y (Fig. 2). Case 3

Four to 8-day cultures were analyzed. All of 30 G-banded metaphases revealed, in a d d i t i o n to a t(11;12)(q23;q13), an interstitial deletion of c h r o m o s o m e 13 similar to that observed in case 2: del(13)(q12q22) (Fig. 3). DISCUSSION

Cytogenetic analyses of over 50 lipomas have been reported [3-5, 11-18], with clonal c h r o m o s o m e rearrangements observed in a p p r o x i m a t e l y 70% of the cases. C h r o m o s o m e 12, more specifically bands 12q13-q14, has been repeatedly involved in reciprocal translocations with a n u m b e r of other chromosomes. Recent reports have identified major cytogenetic subgroups in these benign neoplasms. M a n d a h l et al. [3] classified their cases with chromosomal abnormalities into three groups: those characterized by h y p e r d i p l o i d karyotypes with one or more rings; those with d i p l o i d karyotypes and b a l a n c e d rearrangements of 12q13-14; and those with h y p o d i p l o i d or d i p l o i d karyotypes and aberrations other than rings or rearrangements of 12q13-14. Sait et al. [4] reported three other lipomas with consistent involvement of chromosome 6 at bands p22-p23 in translocations and a duplication. Our data, strengthened by i n d e p e n d e n t reports in the literature [3-5], point to

285

Chromosome 13 Subtype in Lipomas

t__

1

2

3

i--'

4

5

i

11g,, 6

7"

i! 13

14

19

20

8

.

.

.

9

,,

10

1"1

12

16

17

18

.

15

F--j-~ 21

.....

~"--,,.. 22

i ~--I I Y

Figure 3 G-banded karyotype of a cell from case 3 showing the t(11;12)(q23;q13) and del(13)(q12q22) abnormalities.

another distinct subgroup of lipoma with rearrangements involving 13q. Two patients (cases 2 and 3) had an identical cytogenetic change, del(13)(q12q22), and one patient (case 1) had a translocation between chromosomes 8 and 13. Of the cases published, Sandberg et al. [5] reported an inv(13)(q12q32) in a fibrolipoma. Mandahl et al. [3], in their analysis of 35 lipomas, reported a del(13)(q12) in an atypical lipoma and a del(13)(q13q31) in a benign lipoma. Another patient, a 62-year-old male, had a t(13;17) in a benign lipoma; the breakpoint on chromosome 13 in this case was, however, more distal than the others. The clinical, histopathologic, and cytogenetic results of all the cases are shown in Table 1. The lipomas thus seem to comprise a heterogeneous group cytogenetically. The significance of these changes is not clearly understood at present. It may be that they represent different routes for neoplastic transformation of adipose tissue stem cells [3] or they may indicate neoplastic transformation at another stage/cell type in the development of the tumor. None of the three tumors with abnormalities of chromosome 13 studied by Mandahl et al. [3], or the one analyzed by Sandberg et al. [5], was characterized by rearrangements of 12q. One of our cases (case 3), in addition to the interstitial deletion of 13q, showed a translocation of chromosome 11 with chromosome 12 at q13. This would suggest that either two independent events occurred in the same tumor or that one or the other was the primary change with the second abnormality appearing later in the development of the tumor. Because we did not observe any cells with either of the changes as the sole abnormality, we can only speculate as to the primary change. The cytogenetic diversity in lipomas is interesting in view of their benign nature. Malignant changes in a lipoma are exceedingly rare and very few examples have been reported in literature. It is likely that these cases were misdiagnosed. This

286

©

=

t~

©

=.~

~

o--=

~

~"

®I'

.~

7

~?

1~

~ X

re X

X ~

~

~

~ X

X ~

X ~.

~ X

co X

b ~Z ,.m

0 ©

z~

© o ©

% o

b ©

X

X

© .x::

A

o

'~

"~ .~

Chromosome 13 Subtype in Lipomas

287

implies that the genes involved may be proliferation related without leading to malignant transformation. Other benign tumors, such as the m i x e d salivary gland tumors [19, 20] and meningiomas [21], also exhibit cytogenetic variability. Studies directed toward an u n d e r s t a n d i n g of these specific chromosomal changes might be of value in determining factors involved in the malignant process. The abnormalities involving chromosome 13 in the three lipomas s t u d i e d by us and those p u b l i s h e d previously [3, 5] include loss or rearrangement of band 13q14 to w h i c h the retinoblastoma gene (RB1) has been assigned [22]. Homozygous deletion of this locus is postulated to be a primary event in the d e v e l o p m e n t of retinoblastoma and osteosarcoma [23, 24]. Band 13q14 has also been implicated in the t(2;13)(q35;q14) observed in r h a b d o m y o s a r c o m a [25], and in one case of Ewing's sarcoma a del(13)(q13q22) was present as the only cytogenetic change [26]. These findings suggest the possibility of a shared pathogenetic m e c h a n i s m involving this allele by a spectrum of tissues. Loss by deletion or monosomy, or repression and inactivation of this region by chromosomal rearrangements, may have a pleiotropic effect on the d e v e l o p m e n t of soft tissues and other types. The relation of this gene to l i p o m a remains to be investigated by molecular techniques. The observation of more lipomas with similar rearrangements involving chromosome 13 and correlation with various clinical and histologic parameters as well as the behavior of the tumors may lead to a better understanding of the emerging subtypes of lipomas. Molecular analyses might also help to determine if different etiologic m e c h a n i s m s are active in these benign neoplasms. The authors thank Katja Karies and Fred Florhrschutz for photographic assistance and Gayle Corbit for secretarial assistance. This work was supported in part by Grant No. CA-41183.

REFERENCES 1. Enzinger FM, Weiss SW (1988): Soft Tissue Tumors, Second edition, C.V. Mosby, St. Louis. 2. Sandberg AA, Turc-Carel C, Gemmill RM (1988): Chromosomes in solid tumors and be~ yond. Cancer Res 48:1049-1059. 3. Mandahl N, Heim S, Arheden K, Rydholm A, Will~n H, Mitelman F (1988): Three major cytogenetic subgroups can be identified among chromosomally abnormal solitary lipomas. Hum Genet 79:203-208. 4. Sait SNJ, Dal Cin P, Leong SP, Karakousis C, Harris K, Rao U, Sandberg AA (1989): Involvement of 6p in benign lipomas: A new cytogenetic entity? Cancer Genet Cytogenet 37:281283. 5. Sandberg AA, Gibas Z, Saren E, Li FP, Limon J, Tebbi CK (1986): Chromosome abnormalities in two benign adipose tumors. Cancer Genet Cytogenet 22:55-61. 6. Limon J, Dal Cin P, Sandberg AA (1986): Application of long-term collagenase disaggrega° tion for the cytogenetic analysis of human solid tumors. Cancer Genet Cytogenet 23:305313. 7. Seabright M (1971): Rapid banding technique for human chromosomes. Lancet 2:971-972. 8. Peakman DC, Moreton MF, Robinson A (1977): Prenatal diagnosis: Techniques used to help in ruling out maternal cell contamination. J Med Genet 14:37-39. 9. ISCN (1985): An International System for Human Cytogenetic Nomenclature, Harnden DG, Klinger HP (eds.): published in collaboration with Cytogenet Cell Genet (Karger, Basel, 1985); also in Birth Defects: Original Article Series, Vol. 21, no. 1 (March of Dimes Birth Defects Foundation, New York, 1985). 10. Turc-Carel C, Dal Cin P, Rao U, Karakousis C, Sandberg AA (1986): Cytogenetic studies of adipose tissue tumors. I. A benign lipoma with reciprocal translocation t(3;12)(q28;q14). Cancer Genet Cytogenet 23:283-289. 11. Heim S, Mandahl N, Kristoffersson U, Mitelman F, R6~ser B, Rydholm A, Will6n H (1986): Reciprocal translocation t(3;12)(q27;q13) in lipoma. Cancer Genet Cytogenet 23:301-304.

288

c. S r e e k a n t a i a h et al.

12. Heim S, Mandahl N, Kristoffersson U, Mitelman F, ROOser B, Rydhohn A, Will6n H (1987/: Marker ring chromosome a new cytogenetic abnormality characterizing lipogenic tumors? Cancer Genet Cytogenet 24:319-326. 13. Dal Cin P, Turc-Carel C, Sandberg AA (1988): Consistent Involvement of band 12q14 in two different translocations in three lipomas from the same patient. Cancer Genet Cytogenet 31:237-240. 14. Mandahl N, Heim S, Johansson B, Bonnet K, Mortens F, Olsson G, RoOser B, Rydholm A, Will6n H, Mitelman F (1987): Lipomas have characteristic structural chromosomal rearrangements of 12q13-q14. lnt I Cancer 39:685-688. 15. Karakousis CP, Dal Cin P, Turc-Carel C, Limon J, Sandberg AA {1987): Chromosomal changes in soft tissue sarcomas. A new diagnostic parameter. Arch Surg 122:1257-1260. 16. Dal Cin P, Rao U, Tuft-Carol C, Sandberg AA (1988): Translocation (7;21) in a lipoma. Cancer Genet Cytogenet 30:17-22. 17. Jong B De, Castedo SMMJ, Oosterhuis JW, Dam A (1988): Trisomy 7 in a case of angiomyolipoma. Cancer Goner Cytogenet 34:219-222. 18. Turc-Carel C, Dal Cin P, Boghosian L, Leong SP, Sandberg AA (1988): Breakpoints in benign lipoma may be at 12q13 or 12q14. Cancer Genet Cytogenet 36:131-135. 19. Mark J, Dahlenfors R, Ekedahl C (1983): Specificity and implications of ring chromosomes and dicentrics in benign mixed salivary gland tumors. Acta Pathol Microbiol lmmunol Scand A 91:397-402. 20. Mark J, Dahlenfors R (1986): Cytogenetical observations in 100 h u m a n benign pleomorphic adenomas: Specificity of the chromosomal aberrations and their relationship to sites of localized oncogenes. Anticancer Res 6:299-308. 21. AI Saadi A, Latimer F, Madercic M, Robbins T (1987): Cytogonetic studies of h u m a n brain tumors and their clinical significance. II. Meningioma. Cancer Genet Cytogenet 26:127-141. 22. Sparkes RS, Murphree AL, Lingua RW, Sparkes MC, Field EL, Funderburk SJ, Benedict WF (1983): Gene for hereditary retinoblastoma assigned to human chromosome 13 by linkage to osterase D. Science 219:971-973. 23. Cavenee WK, Dryja TP, Phillips RA, Benedict WF, Goodbout R, Gallic BL, Murphree AL, Strong LC, White RL (1983): Expression of recessive alleles by chromosomal mechanisms in retinoblastoma. Nature 3 0 5 : 7 7 9 - 7 8 4 . 24. Hanson MF, Koufos A, Gallic BL, Phillips RA, Fodstad O, Brogger A, Gedde-Dahl T, Cavenee WK {1985): Osteosarcoma and retinoblastoma: A shared chromosomal mechanism revealing recessive predisposition. Prec. Natl. Acad. Sci. USA 82:6216-6220. 25. Douglass EC, Valentine M, Etcubanas E, Parham D, Webber BL, Houghton PJ, Green AA (1987): A specific chromosomal abnormality in rhabdomyosarcoma. Cytogenet Cell Genet 45:148-155. 26. Workman ML, Soukup SW, Neely JE, Whitsett J, Ballard E, Lampkin B (1985): Biologic characteristics of four Ewing's sarcomas. Cancer Genet Cytogenet 15:215-225.