SEARCH

SEARCH BY CITATION

Abstract

  1. Top of page
  2. Abstract
  3. Case Report
  4. Declaration of Interests
  5. References

Two cases of Kaposi’s sarcoma (KS) that occurred in patients who had no evident risk factors for KS but who were former colonists/expatriates in Central Africa are reported. The occurrence of KS in this setting may represent a hitherto unrecognized epidemiological form of KS.

Kaposi’s sarcoma (KS) is a mesenchymal tumor associated with human herpesvirus-8 (HHV-8) infection. Different clinical and epidemiological settings have been identified: (1) acquired immunodeficiency syndrome (AIDS)–associated KS; (2) immunosuppressive drug–related KS; (3) African-endemic KS, which existed for many decades before human immunodeficiency virus (HIV) in some equatorial countries of Africa; and (4) classic KS, which usually follows a benign course and predominantly occurs in elderly men of Mediterranean or eastern European Ashkenazi origin.1,2 KS is not a common disease, and its occurrence out of those contexts is exceedingly rare. I report here two cases of non-HIV-related KS occurring in white Belgian patients who had neither Mediterranean nor Jewish ancestry but who were former colonists/expatriates in Central Africa.

Case Report

  1. Top of page
  2. Abstract
  3. Case Report
  4. Declaration of Interests
  5. References

In 1998, an 84-year-old man presented to our department for purplish plaques and papules on both legs. Between 1947 and 1960, he lived at Stanleyville (currently Kisangani) and used to travel in the neighboring northeastern and northwestern provinces of Congo. During this period, he reported sexual intercourse with more than 30 apparently healthy African women. He was otherwise healthy and took no medication. Skin biopsies of the lesions confirmed the diagnosis of KS and were positive for HHV-8. Serological testing for HIV-1 and HIV-2 was negative.

In 2007, a 74-year-old man presented for the sudden onset of purplish plaques and papules on his upper and lower limbs as well as on his face. Between 1970 and 1973, he lived at Kinshasa and then at Burundi and used to travel in the neighboring northeastern provinces of Congo. He denied having had extraconjugal intercourse. He was taking no immunosuppressive drug, but 1 month before the onset of his lesions, he developed chronic bronchitis for which he was treated with oral methylprednisolone (32 mg/d for 5 d, with subsequent tapering doses). Skin biopsies of the lesions confirmed the diagnosis of KS and were positive for HHV-8. Serological testing for HIV-1 and HIV-2 was negative. Chest computed tomography revealed no evidence of pulmonary KS. His lesions gradually faded without treatment.

A large body of evidence indicates that HHV-8 is the etiological agent of KS.1,2 Cross-sectional epidemiological studies have determined that HHV-8 seropositivity in various populations is strongly correlated with the population’s risk of KS, and several longitudinal studies have shown that HHV-8 precedes the onset of KS. HHV-8 is highly prevalent (14%–100%) among adults in all parts of sub-Saharan Africa but is less common in Western Europe (<2%–10% with regional variation).1 The occurrence of KS in these two patients may thus just reflect residence in “hot spots” for HHV-8 infection. However, HHV-8 infection appears as a very low risk factor for KS development. Assuming a 5% prevalence of HHV-8 in the United States and a 1970s’ baseline incidence of KS in men in the United States of about 0.3 cases per 100,000 men, the HHV-8 rate would be one case of KS in every 17,000 HHV-8 infections.3 In addition, seroprevalence rates in different geographic areas do not always correlate with KS development. For example, the HHV-8 seroprevalence is extremely high in West Africa, whereas AIDS-related KS is rare and endemic KS is not known in these regions.3 Therefore, the geographical distribution of KS is not a simple reflection of the distribution of HHV-8 and points to the role of cofactors in the development of the tumor.4,5 The classification of KS in different epidemiological settings illustrates the key role of factors such as HIV infection, iatrogenic immunosuppression, and Jewish or Mediterranean ancestry in its development.1,2 However, none of our two patients had evident risk factors for KS. Both were HIV-negative Belgian patients and had neither Mediterranean nor Jewish ancestry. The first patient took no medication and the second one was treated by oral methylprednisolone (32 mg/d for 5 d, with subsequent tapering doses) a few days before the onset of his lesions. KS was probably facilitated by steroid therapy in this patient, which is supported by the distribution of his lesions as well as by spontaneous tumor regression after discontinuing the corticosteroid therapy. However, it appeared at a level of iatrogenic immunosuppression much lower than that usually reported for immunosuppressive drug–related KS.6 The first patient reported a high number of sexual partners in Africa, which may have facilitated its disease. However, the second one denied extraconjugal intercourse. Other possible explanations for the development of KS are the acquisition of more pathogenic HHV-8 strains in Central Africa or exposure to some environmental factor. I and others previously suggested that exposure to highly weatherable iron-rich volcanic soils, which are commonly found in the East African rift system, may represent a risk factor for KS development.4,7 The “iron hypothesis” is strengthened by the stimulatory effect of iron salts on KS cell growth and on the production of viral nucleic acids as well as by several observations linking cellular iron content to the development of cancers.8–10

In conclusion, I suggest that long-term residence of Caucasian patients in Central Africa may be a risk factor for KS development and may represent a hitherto unrecognized setting of KS, which can be explained by HHV-8 prevalence rates higher in Africa than in Western Europe or by exposure to some environmental factors or by both.

Declaration of Interests

  1. Top of page
  2. Abstract
  3. Case Report
  4. Declaration of Interests
  5. References

The author states that he has no conflicts of interest.

References

  1. Top of page
  2. Abstract
  3. Case Report
  4. Declaration of Interests
  5. References