Moritz Kaposi was a central physician in the 19th-century development of dermatology. As a leading figure of the Vienna School of Dermatology, he was part of a movement that established the field on a scientific basis, combining clinical observation with pathology. His contributions influenced the understanding of skin diseases well into the 21st century.
The Viennese Dermatologist
Born Móric Kohn in Kaposvár, Hungary, in 1837, he demonstrated early academic promise. He pursued medicine at the University of Vienna, earning his doctorate in 1861. His career path was decisively shaped when he became an assistant to Ferdinand von Hebra, the founder of the influential Vienna School of Dermatology. This mentorship was professional and personal; in 1869, Kaposi married Hebra’s daughter, Martha, after converting to Catholicism.
In 1871, he changed his surname from Kohn to Kaposi, a reference to his Hungarian birthplace. He stated the change was to avoid confusion with several other physicians named Kohn on the Vienna faculty. His career advanced steadily, and he was appointed a professor at the university in 1875. Following Hebra’s death in 1880, Kaposi succeeded him as the chairman of the dermatology clinic at the Vienna General Hospital.
Describing a New Disease
In 1872, Kaposi published a detailed account of a condition he termed “idiopathic multiple pigmented sarcoma of the skin.” This work was based on his meticulous observation of five male patients. The term “idiopathic” was used because its cause was a complete mystery. His paper provided the first clinical description of what would later be known as Kaposi’s sarcoma.
Kaposi documented the illness’s appearance and progression, describing reddish-brown or bluish-red nodules starting on the feet and ankles. These lesions would slowly grow into larger plaques and tumors. He noted that over two to three years, the lesions could spread to the forearms, face, and trunk. An autopsy of one patient who died within 15 months revealed the disease was not confined to the skin, having also affected internal organs like the lungs and gastrointestinal tract.
For nearly a century, the disease was considered a rare, slow-growing cancer affecting elderly men of Mediterranean, Eastern European, or Jewish descent. This form, now called classic Kaposi’s sarcoma, was understood only through Kaposi’s clinical descriptions, as its biological mechanisms were unknown. His work laid the groundwork, but a fuller understanding would not emerge for over one hundred years.
Kaposi’s Sarcoma in the Modern Era
The perception of Kaposi’s sarcoma changed in the early 1980s when physicians reported clusters of this once-rare cancer among young gay men. This aggressive form of the disease became one of the first visible indicators of the Acquired Immunodeficiency Syndrome (AIDS) pandemic. The sarcoma was so closely linked with the syndrome that it became a defining illness for an AIDS diagnosis.
This new context spurred intense scientific investigation, leading to a 1994 breakthrough. Researchers discovered the infectious agent behind the cancer: Kaposi’s sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus 8 (HHV-8). This discovery confirmed that the sarcoma was driven by a viral infection.
It is now understood that HHV-8 infection alone does not cause the disease, as the virus can remain dormant for years. However, when a person’s immune system is severely weakened by HIV or by immunosuppressant drugs used after organ transplants, HHV-8 can activate. The activated virus then drives the abnormal growth of cells lining blood and lymphatic vessels, leading to the lesions of Kaposi’s sarcoma.
Legacy Beyond the Sarcoma
While the sarcoma is his most famous discovery, Kaposi’s contributions to dermatology were far-reaching. He published over 150 papers and books and was among the first to describe several other conditions. These included the systemic manifestations of lupus erythematosus and a rare genetic disorder called xeroderma pigmentosum. His work on xeroderma pigmentosum described its severe photosensitivity and predisposition to skin cancers long before its genetic basis was understood.
In 1880, Kaposi published his principal work, Pathologie und Therapie der Hautkrankheiten (Pathology and Therapy of Skin Diseases). This comprehensive textbook became a standard reference for physicians worldwide and was translated into several languages. Through his clinical work and influential writings, Kaposi helped establish dermatology as a discipline grounded in pathological science, leaving a legacy that shaped the field.