Sternal metastases andassociated pathological fractures · Pathological fractures of the sternumdemonstratea tendency to greater deformity and slower healingthantraumaticsternal fractures.

$Page 1: Sternal metastases andassociated pathological fractures · Pathological fractures of the sternumdemonstratea tendency to greater deformity and slower healingthantraumaticsternal fractures.$
Thorax, 1977, 32, 444-448

Sternal metastases and associated pathologicalfracturesE. P. M. UROVITZ, V. L. FORNASIER, AND A. A. CZITROM

From the Department of Pathology, Princess Margaret and Wellesley Hospitals, and the University ofToronto, Canada

Urovitz, E. P. M., Fornasier, V. L., and Czitrom, A. A. (1977). Thorax, 32, 444-448. Sternalmetastases and associated pathological fractures. A review of 839 necropsies revealed 415 casesof malignant neoplasm, 63 of which were found to have evidence of metastatic spread to thesternum. Nineteen of these metastases resulted in pathological sternal fractures. Fine detailradiography proved a quick and accurate technique for detecting these lesions post mortem. Thecharacteristics of pathological sternal fractures were compared with traumatic sternal fractureswith respect to deformity and healing. Pathological fractures of the sternum demonstrate a

tendency to greater deformity and slower healing than traumatic sternal fractures.

There is a paucity of published information re-garding the incidence of sternal metastases. Evenless is known about the incidence of pathologicalfractures (meaning, in this study, fractures sec-ondary to metastatic tumour). The reasons forthis gap in our knowledge are twofold: first,metastatic tumours and pathological fractures ofthe sternum are rare (Gompels et al., 1972) andthere has been an insufficient amount of histo-logical material available to enable conclusionsabout the incidence to be reached; secondly, areliable and rapid method of determining thepresence of these lesions has not been widely used.It is our purpose in this communication to reportthe incidence of metastases and of pathologicalfractures of the sternum derived from a largenecropsy series of a cancer institute (PrincessMargaret Hospital) and a general hospital(Wellesley Hospital), to characterise the patho-logical fractures according to site and deformity,and to outline a quick and reliable technique fordetermining the presence of these lesions.

Material and methods

It is routine procedure at necropsies performed atthe Princess Margaret and Wellesley Hospitals toremove the sternum from each cadaver and, afterexamining it grossly, to make sagittal sectionsof the excised sternum approximately 4 mm thickwith a band saw. These sections are radiographedusing a Faxitron 805 automatic x-ray unit andeither mammography film or Kodak SR54 in-

dustrial x-ray film. If mammography film is used,this is processed in an Xomat automatic developer;if Kodak SR54 is used, this must be wet processed.The sagittal sections and radiographs are thencompared and histological sections are taken fromany suspected metastasis and pathologicalfracture.Fine detail radiographs of sterna removed at

necropsy during the years 1974, 1975, and thefirst six months of 1976 were examined with thenaked eye and under low magnification with ahand lens to identify any lesion suggestive of ametastasis. A simultaneous examination of finedetail radiographs of thoracolumbar spines wasalso performed to add further information aboutbony metastases (Fornasier and Horne, 1975). Anattempt was then made to correlate the incidenceof metastases determined by fine detail radio-graphy with that detected by histological exam-ination as recorded in the case file.

Pathological fractures were easily detectedusing fine detail radiographs. The incidence ofsuch fractures was recorded and a comparativestudy of these fractures with known traumaticsternal fractures discovered in the same necropsypopulation was undertaken in an attempt to gainsome understanding of the pathogenesis of suchpathological fractures.

Results

A total of 839 necropsies were reviewed and 415cases of malignancy recorded (Table 1). This ex-

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Sternal metastases and associated pathological fractures

Table 1 Comparison of histological and radiologicalevidence of metastasis in 415 cases of malignantneoplasm

Evidence ofmetastases %Primary tumour No of cases

Histological FDR

Breast 84 31 26Lymphoma 84 35 10Lung 54 15 11Colon 42 4 4Ovary 36 2 2Prostate 18 18 16Kidney 16 25 25Myeloma 13 30 30Uterus/cervix 12 16 16Stomach 12 25 25Melanoma 10 30 30Bladder 10 0 0Oesophagus 6 0 0Pancreas 6 0 0Oropharynx 5 40 40Thyroid 4 50 50Testis 2 0 0Adrenal 1 0 0

tremely high incidence reflects the nature of a

cancer institute like the Princess MargaretHospital. Of the 415 cases of malignancy, 63 weremetastases to the sternum. As seen in Table 1,there was a relatively high correlation betweenmetastases diagnosed by fine detail radiographyand those diagnosed by histological examination,with the exception of lymphoproliferative diseases.This exception comes as no surprise as, in a pre-vious paper, Fornasier and Home (1975) reported

a similar low correlation between fine detailradiography and histological examination in thediagnosis of lymphomatous vertebral metastases.As in the previous study, we think that the abilityof the lymphomas to infiltrate without causingexcessive trabecular destruction is the explanationfor the low rate of detection by fine detailradiography.

In using this technique it became apparent thatone had to distinguish between the frequent ovaltransradiant areas which are a normal part of thesternal body architecture and the irregular areaswhich characterise a true metastasis (Fig. 1(centre and right)). This rarely posed a problem,especially as we gained experience in examiningthe fine detail radiographs.There were no pulsatile lesions in our cases

even in association with metastases from renaladenocarcinomas and thyroid carcinomas (Kinsellaet al., 1947).

In addition, 95% of metastases in this seriesoccurred in the body of the sternum and only 5%in the manubrium which is a much greater rela-tive incidence than was previously reported (Kin-sella et al., 1947).

In this review, a total of 34 sternal fractureswere discovered, of which seven could be tracedto a previous history of trauma (example: cardio-pulmonary resuscitation), eight had no knownaetiology, and 19 were fractures secondary tometastatic tumour deposits. The primary tumour

Fig. 1 Fine detail radiographsof sterna showing (left) apathological fracture of themanubrium due to Ewing'ssarcoma (centre) a normalpattern of central transradiance,and (right) mottled destructionand sclerosis of the manubriumin a case of multiple myeloma.The transradiant areasassociated with deposits ofmultiple myeloma are irregularin outline, and associated withdisruption of the normaltrabecular pattern (X2).

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site in these cases of pathological fracture isshown in Table 2. As could be expected from thepreponderance of secondaries found in the bodyof the sternum, 18 of 19 fractures occurred in thebody. The single case of manubrial fracture wasdue to Ewing's sarcoma (Fig. 1 (left)).

Table 2 Primary tumour site in 19 pathologicalsternal fractures

Breast 10 Tonsil 1Cervix I Ewing's sarcoma ILymphoma 2 Myeloma 2Caecum I Renal adenocarcinoma I

In order to characterise these fractures we com-pared them with a series of known traumatic frac-tures with respect to deformity and healing. Wegrouped the eight cases in which no definiteaetiology could be established with the seven casesof known trauma: in the absence of pathologicalchange in the sternum, trauma was considered themost likely cause of the fracture.

Deformity involves both displacement andangulation. We defined the fracture as signifi-cantly deformed if on examination of the finedetail radiograph there was greater than 05 cmof displacement and/or greater than 150 ofangulation.On applying these criteria we discovered that

pathological fractures cause deformation andmalalignment more often than the low velocitytraumatic fractures seen in this series. Twelveof 19 pathological fractures showed significantdeformity; four showed anterior displacementwithout angulation; one showed posterior dis-placement without any angulation; six demon-strated posterior angulation without anydisplacement; and one showed significant posteriordisplacement with posterior angulation. Of thetraumatic fractures, only four of 15 demonstratedsignificant deformity, and three showed posteriorangulation of the distal fragment.A comparison of the degree of healing between

traumatic and pathological fractures was made.We subdivided the healing and remodellingprocesses into three stages, depending upon histo-logical and radiological evidence of callus forma-tion: stage 1-complete or almost completehealing: abundant callus formation with oblitera-tion of fracture lines; stage 2-partial healing:initial callus formation with clouding of fracturelines on the radiograph and obvious organisinggranulation tissue on histological sections; stage3-little or no healing: minimal or no evidence

of callus formation with clear fracture lines onthe radiograph and little granulation tissue onhistological sections. All fractures showed at leastsome tissue reaction at the cortical margins, there-by eliminating the inclusion of traumatic frac-tures, produced at necropsy, from this series.

Applying these criteria, we found a muchgreater tendency to slow healing in the patho-logical fracture group, in which 12 of 19 fell intostage 3. Examples of unhealed and healed patho-logical fractures are shown in Figure 2.On the other hand, only four of 15 traumatic

fractures fell into stage 3, and in these cases thefracture was of very recent onset (for example,postcardiac resuscitation), thereby negating anypossibility of normal fracture healing).

Fig. 2 Fine detail radiographs of sternal fractures.Lysis of both trabecular and cortical bone but littlecallus formation can be seen in the early pathologicalfracture (left). Malunion with gross anteriordisplacement and healing by well organised callus ispresent (right) (X2).

Discussion

Metastatic tumours of the sternum are rare. In1947 Kinsella et al. compiled a review of the

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published cases. They collected a total of 67 casesof metastatic sternal lesions and stated that thy-roid carcinoma appeared to be the most frequentprimary tumour, while the kidney and breastfollowed in frequency as primary sites. In addi-tion, they concluded that the manubrium wasinvolved more often than any other anatomicalportion of the sternum. Neither in that report,nor in any others, was an attempt made to des-cribe and record the incidence of sternal meta-stases in specific neoplastic disorders. Thus, theclinician lacked information regarding the prob-ability of discovering a secondary lesion inpatients with known malignancy presenting withsymptoms referable to the sternum.Our findings differ from past reports in a num-

ber of ways. First, we found that the most com-mon primary tumour site for sternal disseminationwas breast, not thyroid (ratio 22: 2). We thinkthe explanation of this phenomenon is that thePrincess Margaret Hospital is a regional cancercentre and breast carcinoma is the most fre-quently treated malignancy. In addition, an in-crease in the incidence of breast carcinoma hasbeen noted in recent years (Savlov, 1971). Never-theless the small number of cases of thyroid car-cinoma have an unusually high incidence ofsternal metastases (50%) in our series.

Secondly, the rise in incidence of carcinoma ofthe lung probably explains our findings of largenumbers of sternal metastases secondary to thistumour as compared to its low incidence in earlierstudies (Macey and Phalen, 1943).

Contrary to previous reports, we have foundthe vast majority of sternal metastases to be in thebody of the sternum as opposed to the manu-brium. Even our cases of sternal metastases sec-ondary to renal adenocarcinoma and thyroidcarcinoma disseminated to the body.There is no mention of the incidence of patho-

logical sternal fractures in Kinsella's (1947) studyor in any other studies dealing with sternal meta-stases; indeed, discussion of this aspect is verylimited (Gompels et al., 1972; Law and Jones,1975). Our series is admittedly a small one butcertain features should be noted. We found 19cases of pathological fracture of the sternumamong 63 cases of metastases. Breast carcinomaaccounted for slightly more than half of thefractures. These fractures tend to be characterisedby slow healing and continued deformity, andobviously unless the metastasis itself is adequatelytreated the chances of healing are limited. Sub-periosteal new bone formation and callus can beseen but it is generally believed that effective im-

mobilisation of the fracture lines cannot beobtained (Cruess, 1975).The expansion of the tumour outside the cortex

probably further impedes healing and contributesto deformity by allowing the unhealed fractureends to be altered according to deforming forcessuch as coughing (Bass and Small, 1952) and thecyclic stresses of respiration.

Conclusions

1 Sixty-three cases of sternal metastases werediscovered in reviewing 415 cases of malignancy.2 There was a high correlation between fine de-tail radiography and histological diagnosis ofmetastases, thus confirming that fine detail radio-graphy is a quick and relatively accurate techniquefor necropsy diagnosis.3 A total of 34 sternal fractures were foundamong the 839 necropsies, of which 15 weretraumatic in origin and 19 were pathological.4 Pathological fractures are characterised byslow healing and a tendency to deformity as com-pared to low velocity traumatic sternal fractures.

References

Bass, H. E., and Small, M. J. (1952). Spontaneousfracture of the sternum in tuberculosis. Journal ofthe American Medical Association, 150, 209-210.

Crile, G. (1936). Pulsating tumors of the sternum.Annals of Surgery, 103, 199-209.

Cruess, R. L. (1975). Healing of bone, tendon andligament. In Fractures, edited by C. A. Rockwood,Jr., and D. P. Green. Lippincott, Philadelphia andToronto.

Fornasier, V. L., and Horne, J. G. (1975). Metastasesto the vertebral column. Cancer, 36, 590-594.

Gompels, B. M., Votaw, M. L., and Martel, W. (1972).Correlation of radiological manifestations ofmultiple myeloma with immunoglobulin abnormali-ties and prognosis. Radiology, 104, 509-514.

Hedblom, C. A. (1921). Tumors of the bony chestwall. Archives of Surgery, 3, 56-85.

Heuer, G. J. (1932). The tumors of the sternum; re-port of removal of large mediastinal sternal chon-dromyxoma. Annals of Surgery, 96, 830-842.

Kinsella, T. J., White, S. M., and Koucky, R. W.(1947). Two unusual tumors of the sternum. Journalof Thoracic Surgery, 16, 640-667.

Law, I. P., and Jones, C. (1975). IgA myeloma andsternal fracture. (Letter) Journal of the AmericanMedical Association, 233, 767-768.

Macey, H. B., and Phalen, G. S. (1943). Metastaticlesions of the sternum. Surgery, Gynecology andObstetrics, 76, 453-455.

Parham, F. W. (1889). Thoracic resection for tumoursgrowing from the bony wall of the chest. Transac-

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tions of the Southern Surgical and GynecologicalAssociation, 11, 223.

Savlov, E. (1971). Breast cancer. In Clinical Oncologyfor Medical Students and Physicians: A Multi-disciplinary Approach, 3rd edition, edited by P.Rubin and R. F. Bakemeier, p. 90. American Can-cer Society, Rochester.

Sommer, G. N. J., Jr., and Major, R. C. (1942).Neoplasms of the bony thoracic wall. Annals ofSurgery, 115, 51-83.

Requests for reprints to: Dr. V. L. Fornasier, Depart-ment of Pathology, The Princess Margaret Hospital,500 Sherbourne Street. Toronto, Canada M4X IK9.

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