|
| Fig. 20.5 Hair loss in cancer therapy. A, Anagen effluvium. The shaft tapers down to a pencil-like point and easily separates from the follicle. B, Normal telogen hair. About 50 to 100 telogen hairs such as these are normally shed during the course of the day. Much higher numbers are shed during a telogen effluvium. |
Cancer patients are susceptible to two forms of diffuse hair loss.
Anagen effluvium is a direct effect of anticancer treatment. Patients receiving radiation therapy to the scalp or systemic chemotherapy can shed all or most of their hair within a few weeks of starting treatment. This hair loss is a direct effect of the chemotherapy or radiotherapy on the hair follicle, whose rapidly dividing cells are very susceptible to injury. When the hair matrix (the epithelial root that produces the hair shaft) is exposed to radiation or chemical toxins, it can only produce a thinned hair shaft that eventually tapers to a point (Fig. 20-5A). This marked tapering makes the shaft extremely fragile, and the hair shaft can literally be combed away or broken off by minor trauma. Unless the dose of radiation or chemotherapy is very high, regrowth of hair occurs once therapy is stopped.
In
telogen effluvium the metabolic and emotional “stress” of severe, debilitating illness causes many of the actively growing (anagen) hairs to enter the shedding (telogen) phase of hair growth prematurely. The hairs remain in telogen for about 3 months before they are finally shed (Fig. 20-5B), so there is always a “lag” time between the onset of severe disease and actual hair loss. Seldom is more than 50% of the hair shed in telogen effluvium, so patients develop thin hair but do not become completely bald. If the patient recovers and is no longer debilitated, hairs reenter the actively growing phase and the hair regrows.
Kligman AM: Pathologic dynamics of human hair loss: I. Telogen effluvium, Arch Dermatol 83:175–198, 1961.
