Incidence of normal pineal gland calcification in skull roentgenograms of black and white Americans.

H UMAN pineal gland calcification, which was reported in autopsy specimens about 300 years ago, was first described in the plain skull roentgenogram in 1918 by Sch#{252}ller,’6 who remarked that the gland “very often shows a calcium deposit from the third decade and occasionally even in children.” Subsequent workers confirmed Sch#{252}ller’s observation and established the influence of age on the incidence of pineal gland calcification.6’7”3”7”8 From a summary of several of these works, the estimated frequency of pineal shadow was found to be 2 per cent in those 3 to 12 years of age; 46 per cent from 13 to 40; and 69 per cent after the age of 40.20 All the above studies were carried out mainly in Caucasians, and racial differences were not mentioned. In recent years, a much lower incidence of pineal gland calcification has been reported in other races: 9.9 per cent in Japanese;4 15.6 per cent in Fijians;” and 19-24 per cent among Indians.”5 In Africa, one of the first hints of a low incidence of pineal shadow was made by Odeku and J anota’4 in their study of brain tumors at the University College Hospital, Ibadan, Nigeria. They mentioned a surprising rarity of calcified pineal gland on skull roentgenograms in West Africans. At the same hospital, where an average of about 2,000 skull roentgenographic examinations are made every year, Adeloye and Odeku2 encountered less than 10 cases of roentgenologically visible calcified pineal gland in the neurosurgery unit during a period of 10 years. These impressions have been confirmed by Daramola and Olowu,5 who, in their study of 952 skull roentgenograms obtained in Nigerians in Lagos, found a calcified pineal shadow in per cent. In East Africa, Murphy,’2 a radiologist at the Mulago Hospital in Kampala, Uganda, found only 2 examples of calcified pineal gland in a series of 100 consecutive skull examinations obtained from 88 East Africans, 9 Asians, and 3 Europeans between ‘7 and 62 years ofage. Although he did not identify the racial origin of the 2 patients, any mode of mathematical manipulation would still make the incidence of pineal gland calcification remarkably low in the East African. Pineal gland calcification is not necessarily indicative of pineal gland atrophy, at least by biochemical and histologic evidence.20 A recent pathologic study showed that microscopic pineal gland calcification occurs in Nigerian Africans in every decade from the first to the ninth.2 The paradoxical rarity of gross, roentgenographically visible pineal gland calcification remains unexplained. The purpose of the present study is to compare the incidence of the calcified pineal gland shadow between black and white populations living in a similar environment, to determine if there is truly a lower incidence of visible pineal gland calcification among blacks and if so, to seek an explanation for it.