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February iotaderma (#276)
JAAD ONLINE: IOTADERMA IOTADERMA #277 If you’ve read the Iliad, you should remember that Achilles was the leader of the Greek troops known as the Myrmidons. To what does the term myrmecia refer to in dermatology (they come from the same Greek root word)? Robert I. Rudolph, MD, FACP Answer will appear in the JAAD Online section of the April issue of the Journal.
FEBRUARY IOTADERMA (#276) All dermatologists know what larva migrans is, what various helminthic organisms are causative, and what it looks like clinically. But do you know why larva migrans exists as it does? Answer: The current opinion is that that some varieties of helminthic larvae, while capable of producing a large number of proteinases, cathepsins, hyaluronidases, and other enzymes that allow them to exsheath and begin their migration from the skin to their internal target organs, fail to produce an effective basement membrane zone (BMZ) collagenase.1 The adult worms, however, can and do produce the full array of such destructive proteins, and can easily migrate internally.2 The total lack of any larval collagenolytic activity, however, suggests that dissolving the large major BMZ structural proteins, such as laminin and elastin, as well as other BMZ components, is not possible for larvae. Penetration through the BMZ and into the dermis is inhibited, and the living larvae have to remain above the unbreached BMZ. They are therefore limited to a rather inhospitable intraepidermal milieu, and the body’s inflammatory reaction to their foreign constituents is what causes the disease we see clinically (personal communication from Dr Helmut Albrecht, March 2016).3 REFERENCES 1. Wertheim G, Lustigman S, Silberman H, Shoshan S. Demonstration of collagenase activity in adult Strongyloides ratti (Nematoda: Strongyloididae) and its absence in the infective larvae. J Helminthol 1983;57:241-246. 2. Hotez P, Haggerty J, Hawdon J, et al. Metalloproteases of infective Ancylostoma hookworm larvae and their possible functions in tissue invasion and ecdysis. Infect Immun 1990;58:3883-3892. 3. Albrecht H, Franco-Paredes C. Cutaneous larva migrans. Available at: http://www. antimicrobe.org/b08.asp. Accessed July 31, 2016.
Robert I. Rudolph, MD, FACP
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FEBRUARY IOTADERMA (#276) All dermatologists know what larva migrans is, what various helminthic organisms are causative, and what it looks like clinically. But do you know why larva migrans exists as it does? Answer: The current opinion is that that some varieties of helminthic larvae, while capable of producing a large number of proteinases, cathepsins, hyaluronidases, and other enzymes that allow them to exsheath and begin their migration from the skin to their internal target organs, fail to produce an effective basement membrane zone (BMZ) collagenase.1 The adult worms, however, can and do produce the full array of such destructive proteins, and can easily migrate internally.2 The total lack of any larval collagenolytic activity, however, suggests that dissolving the large major BMZ structural proteins, such as laminin and elastin, as well as other BMZ components, is not possible for larvae. Penetration through the BMZ and into the dermis is inhibited, and the living larvae have to remain above the unbreached BMZ. They are therefore limited to a rather inhospitable intraepidermal milieu, and the body’s inflammatory reaction to their foreign constituents is what causes the disease we see clinically (personal communication from Dr Helmut Albrecht, March 2016).3 REFERENCES 1. Wertheim G, Lustigman S, Silberman H, Shoshan S. Demonstration of collagenase activity in adult Strongyloides ratti (Nematoda: Strongyloididae) and its absence in the infective larvae. J Helminthol 1983;57:241-246. 2. Hotez P, Haggerty J, Hawdon J, et al. Metalloproteases of infective Ancylostoma hookworm larvae and their possible functions in tissue invasion and ecdysis. Infect Immun 1990;58:3883-3892. 3. Albrecht H, Franco-Paredes C. Cutaneous larva migrans. Available at: http://www. antimicrobe.org/b08.asp. Accessed July 31, 2016.
Robert I. Rudolph, MD, FACP
e101