Skin nontumor
Infestations
Scabies (mite)
Topic Completed: 1 July 2011
Minor changes: 3 March 2020
Copyright: 2002-2020, PathologyOutlines.com, Inc.
PubMed Search: Scabies[TI] mite[TI]
See Also: Penis & scrotum chapter
Table of Contents
Definition / general | Pathophysiology | Diagrams / tables | Case reports | Treatment | Microscopic (histologic) description | Microscopic (histologic) images | VideosCite this page: Hamodat M. Scabies (mite). PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/skinnontumorscabies.html. Accessed August 7th, 2020.
Definition / general
- Mite that produces burrows and extremely pruritic erythematous papules on interdigital skin, palms, wrists
Pathophysiology
- Sarcoptes scabei spend their entire lifecycle on or in their human host (Pritt: Creepy Dreadful Wonderful Parasites Blog - Answer to Case 531 [Accessed 29 August 2019])
- Female burrows into the outermost layer of the epidermis (the stratum corneum) to create a short burrow called a molting pouch
- Male penetrates this pouch and mates with the female
- Dispersed along the burrows are eggs, hatched larvae and excrements
- Scabies mites generally do not survive > 2 - 3 days away from human skin (CDC: Scabies - Prevention & Control [Accessed 29 August 2019])
- Can survive longer in some cases (Pritt: Creepy Dreadful Wonderful Parasites Blog - Answer to Case 531 [Accessed 29 August 2019])
Diagrams / tables
Images hosted on other servers:
Life cycle
Case reports
- Elderly man with objects found in skin scrapings (Pritt: Creepy Dreadful Wonderful Parasites Blog - Case of the Week 531 [Accessed 29 August 2019])
Treatment
- Topical permethrin (Can Fam Physician 2010;56:1005)
Microscopic (histologic) description
- Burrow containing mite body parts appears as cleft in upper epidermis
- Epidermis exhibitis acanthosis, parakeratosis, spongiosis, with dense eosinophilic dermal infiltrate
- In the dermis, there is superficial perivascular and sometimes diffuse infiltrate of lymphocytes and histiocytes, sometimes accompaned by neutrophils and less often eosinophils
- In nodular skin lesions, the dermal infiltrate may be very dense and atypical and hyperchromatic cells may be evident, in addition to histiocytes, plasma cells, eosinophils and lymphocytes
- Mites (Pritt: Creepy Dreadful Wonderful Parasites Blog - Answer to Case 531 [Accessed 29 August 2019]):
- Male mites range in size from 213 - 285 μm long by 162 - 240 μm wide
- Female mites range from 300 - 504 μm long to 230 - 420 μm wide
- Sarcoptes are round to ovoid when viewed from the back; when viewed from the side they are ventrally flattened and dorsally rounded (similar to a turtle)
- They possess short stumpy legs and have no internal or external respiration apparatus (stigmata or tracheae)
- Ventral surface contains a number of chitinized plates called apodemes, the dorsal surface is partially covered by wide angled, V shaped spines
- Cuticular surface is sculptured into numerous parallel ridges which superficially resemble human finger prints and the anus is at the posterior end of the mite
- The last segment (tarsus) of legs 1, 2 and 4 on males and legs 1 and 2 on females has a long, unjointed empodium or stalk with a small sucker-like pad at its end
- These stalks are diagnostic for Sarcoptes
Microscopic (histologic) images
Contributed by Bobbi Pritt, M.D.
Sarcoptes scabei var. hominis: mites, eggs and fecal pellets (scybala)
Contributed by Dr. Daniel Ostler
Images hosted on other servers:
Mite
Videos
Sarcoptes scabei var. hominis
