EXPERIMENTAL AND MOLECULAR PATHOLOGY 1, 288-292 (1962)

Hyaline Arteriolosclerosis in the Spleen

II. A Comparative Study of Africans in Uganda and

Europeans in London

BRIAN MCKINNEY

Department of Pathology, Makerere Medical College, Kampala, Uganda

Received February 10, 1962

INTRODUCTION

Much has been written on the pathogenesis of hyaline arteriolosclerosis (Duguid and Anderson, 1952; Still and Hill, 1959) and it is thought to have a similar origin to atheroma (Duguid, 1952) in that both appear to originate from fibrin and allied substances deposited from the blood stream (McKinney, 1962a). As the incidence and severity of aortic atheroma appears to be less in Uganda Africans (McKinney, 1961) than in previous studies of Europeans (Hill et al., 1961) it seemed that a similar state of affairs might exist for hyaline arteriolosclerosis.

There is only one mention of studies on the incidence of hyaline arteriolosclerosis in Negroes and Europeans (Moritz and Oldt, 1937), but here no differences were found. This study was however carried out in America where, due to the fact that much intermarriage has taken place, one is presumably not dealing with a pure Negro stock.

It was therefore thought worthwhile to carry out a study of Africans in Uganda and to compare these results with a similar group of Europeans in London.

METHODS AND MATERIALS

Splenic tissue was obtained from 101 post-mortems carried out in Mulago Hospital in Kampala, Uganda during 1961. The material was fixed in 10% formol-saline and embedded in paraffin wax. A minimum of three sections of each spleen (including the capsule) were examined. The definitions of type of vessel and amount of hyaline arteriolosclerosis present were similar to that which has previously been described (McKinney, 1962b). All these African cases were then matched, as nearly as pos- sible, with 100 similar cases in London. All the results were transcribed onto punch cards and sorted, as desired, on a Power-Samas card sorter.

RESULTS

TRABECULAR ARTERIES

Tables I and II show that no hyaline arteriolosclerosis was found in normotensives aged less than 11 years in either Europeans or Africans. After this age it will be seen that hyaline arteriolosclerosis may be found in both Europeans and Africans but that it appears to be more severe and frequent in the former. Thus 7.4% of

288

HYALINE ARTERIOSCLEROSIS IN SPLEEN. II 289

TABLE I

TRABECULAR ARTERIES

Age group

Total number of cases

Degree of hyalinosis

0 k +

Normotensives:Africans

++

O-10 11 11 (100)a - - -

11-30 27 23 (85.2) 4 (14.8) - -

31-50 28 10 (35.7) 15 (53.6) 3 (10.7) -

51-70 8 5 (62.5) 2 (25) l(l2.5) - - 74

Normotensives:EuroDeans

O-10 12 12 (100)a - - -

11-30 27 22 (8l.S) 3 (11.1) 2 (7.4)

31-50 18 10 (55.6) 4 (22.2) 3 (16.7) 1 (5.5) 51-70 8 l(12.5) 5 (62.5) 2 (25) -

-

65

Hypertensives:Africans

O-10 - - - - 1 l-30 7 5 (71.4)” 1 (14.3) 1 (14.3) -

31-50 15 3 (20) 8 (53.3) 4 (26.7) -

51-70 5 - - 5 (100) -

27

Hypertensives : Europeans

O-10 - - - - -

11-30 6 2 (33.3) 2 (33.3) 2 (33.3) -

31-50 17 5 (29.4) 5 (29.4) 6 (35.3) l(S.9)

51-70 12 5 (41.7) 1 (8.3) 3 (25) 3 (25)

35

a Percentages shown in brackets.

European cases in the 1 l-30 age group showed a + degree of hyaline arteriolosclerosis while none could be seen in the African cases studied.

In the hypertensive cases there did not appear to be the same differences in incidence of hyaline arteriolosclerosis but a more severe degree of hyaline arteriolo- sclerosis was more commonly found in Europeans than in Africans. Thus in the 31-50 age group 41.2% of the European cases studied showed a + or ++ degree of hyalinosis compared with only 26.770 in African cases.

FOLLICULAR ARTERIOLES

In normotensives the same pattern was seen as in the trabecular arteries (Table 11). For example, in the 11-30 age group 88.9% of the Europeans showed some hyaline arteriolosclerosis while only 40.6% of the Africans in the same age group showed this vascular change. The degree of hyaline arteriolosclerosis was also more marked in the Europeans than in the Africans studied.

In the hypertensive groups it was noted that there was not as much difference as

290 BRIAN MC KINNEY

TABLE II

FOLLICULAR ARTERIOLES

Age grow

Total number of cases 0

Degree of hyalinosis

-c + ++

Normotensives:Africans

c-10 11 11 (100)a - - - 1 l-30 27 16 (39.4) 8 (29.5) 3 (11.1) - 31-50 28 7 (25) 8 (28.6) 13 (46.4) - 51-70 8 1 (12.5) 5 (62.5) 2 (25) -

- 74

Normotensives:Europeans

c-10 12 12 (100)a - - -

1130 27 3 (11.1) 8 (29.6) 14 (51.9) 2 (7.4) 31-50 18 1 (5.5) 4 (22.2) 12 (66.8) 1 (5.5)

51-70 8 - l(12.5) 5 (62.5) 2 (25) 65

Hypertensives:Africans

&IO - - - - 11-30 7 2 (28.6)‘J 3 (42.8) 2 (28.6) -

31-50 15 - 3 (20) 9 (60) 3 (20) 51-70 5 - - 1 (20) 4 (80)

27

Hypertensives:Europeans

O-10 - - - - 1 l-30 6 - 1 (16.7)a 4 (66.6) 1 (16.7) 31-50 17 1 (5.8) 3 (17.6) 10 (59.0) 3 (17.6)

51-70 12 1 (8.3) - 8 (66.7) 3 (24)

35

a Percentages shown in brackets.

in the normotensive groups and that both Europeans and Africans exhibited a roughly similar incidence except in the 11-30 age group where a higher incidence and severity of hyaline arteriolosclerosis was found in Europeans than Africans.

PULP ARTERIOLES

Here it was seen that hyaline arteriolosclerosis occurred both more frequently and more severely in Europeans than in Africans in both normotensive and hypertensive groups (Table III). It should also be noted that in the 1 I-30 age group of hyper- tensives there is a marked increase in both incidence and severity of hyalinosis which is not seen in the other groups. NO similar finding was noted among the Africans studied as can be seen from Table III.

The only other factor which appeared to have any effect on hyaline arteriolo- sclerosis of the spleen were (1) diabetes which appears to increase both the severity and frequency, and (2) the malignant reticuloses which diminish both the frequency and severity of these vascular changes.

HYALINE ARTERIOSCLEROSIS IN SPLEEN. II 291

TABLE III

PULP ARTERIOLES

Age group

Total number of cases 0

Degree of hyalinosis

+ + ++

Normotensives:Africans

O-10 11 11 (100)U - - -

11-30 27 24 (88.9) 3 (11.1) - -

3 I-50 28 19 (67.9) 5 (17.8) 4 (14.3) 51-70 8 7 (87.5) l(12.S) - -

74

Normotensives:Europeans

O-10 12 12 (100)a - - -

11-30 27 13 (48.11) 9 (33.3) 4 (14.8) 1 (3.8)

31-50 18 6 (33.3) 8 (44.4) 3 (16.7) l(S.6)

51-70 8 2 (25) 4 (50) 1 (12.5) l(12.5)

65

Hypertensives:Africans

O-10 - - -

11-30 7 5 (71.4)& 2 (28.6) -

31-50 15 7 (46.6) 4 (26.7) 4 (26.7) 51-70 5 - 1 (20) 4 (SO) -

27

Hypertensives:Europeans

O-10 - - - -

1 l-30 6 - 4 (66.6)a 1 (16.7) 1 (16.7)

3 l-50 17 4 (23.5) 6 (35.3) 6 (35.3) 1 (50.9)

51-70 12 1 (8.3) 5 (41.7) 4 (33.3) 2 (16.7)

35

a Percentages shown in brackets.

DISCUSSION

It will be noted that in Africans as in Europeans the two factors which appear principally responsible for the production of hyaline arteriolosclerosis are age and hypertension. Diabetes also appears to increase hyaline arteriolosclerosis while the malignant reticuloses decrease it but the number of cases was too small for any definite figures to be obtained. These findings are similar to those which have been observed previously (McKinney, 1960).

It is difficult to ascertain why the amount of hyaline arteriolosclerosis is diminished in Africans as compared with Europeans but, if Duguid’s theory of the pathogenesis of hyaline arteriolosclerosis is correct, then it would seem that the amount of circu- lating hbrinolysins might be higher in Africans. Studies on this point are being carried out here but at present no definite results have been obtained.

292 BRIAN MC KINNEY

SUMMARY

A comparative study of the splenic arteries and arterioles in 101 Africans from Uganda and a similar number (100) of European cases from London is reported.

It was found that the amount of hyaline change both as regards incidence and severity, is less in Africans, particularly in normotensives.

The two principal etiological factors, namely age and hypertension, are similar to both racial

groups. No other diseases have been established as having a definite role although it seems possible that

diabetes mellitus increases and the malignant reticuloses decrease the incidence and severity of hyaline arteriolosclerosis.

It is suggested that the raised fibrinolysin levels found in Africans may be largely responsible for the differences found between them and Europeans.

ACKNOWLEDGMENTS

I would like to thank the staff of the Pathology Department, Makerere College for preparing the sections used in this study. I would also like to thank Mr. Rowland Hurst of the Finance Department, The Royal Free Hospital, London, for his assistance in this study by providing and using the Power-Samas card sorter as described above.

REFERENCES

DUGUID, J. B. (1952). Lancet ii, 207-208. DUCUID, J. B., and ANDERSON, C. S. (1952). J. Pathol. Bacterial. 64, 519-522. HILL, K. R., CAMPS, F., RIGG, K., and MCKINNEY, B. (1961). hit. Med. J. 1, 1190-1193. MCKINNEY, BRIAN (1960). M.D. Thesis, University College, Dublin, Ireland. MCKINNEY, BRIAN (1961). Unpublished observations. MCKINNEY, BRIAN (1962a). J. Pathol. Bacterial. In press. MCKINNEY, BRIAN (1962b). Hyaline arteriolosclerosis in the spleen. Exptl. Mol. Pathol. 1, 2

287. MORITZ, A. R., and OLDT, M. C. (1937). Am. J. Pathol. 13, 679-728. STILL, W. J. S., and HILL, K. R. (1959). Arch. Pathol. 68, 42-48.

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