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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_182_библиотеки_им_акад_М_И_Перельмана.pdf
(Left) Cysticerci in striated
p
muscle can be numerous
and are rarely symptomatic.
(Courtesy Franz von
Lichtenberg Collection of ID
Pathology, BWH.) (Right) AP
radiograph reveals multiple
ovoid calcifications oriented
along the long axis of the
muscle fibers of the thighs .
The appearance is classic for
cysticercosis. (From DI: MSK
Helminthic Parasitic Infections: Cestodes
Non-Trauma.)
(Left) Massive numbers of
cysticerci are present in
this autopsy brain section.
This disseminated form of
neurocysticercosis is rare and
only seen in patients from
endemic areas. (Courtesy
Franz von Lichtenberg
Collection of ID Pathology,
BWH.) (Right) MR shows
innumerable cysts, each with
a hyperintense scolex in this
atient with neurocysticercosis
from Mexico. (From DI2:
Brain.)
CYSTICERCOSIS
Microscopic, Radiologic, and Gross Features
(Left) Gross pathology shows
a translucent cyst with a
characteristic invaginated
white scolex diagnostic
of neurocysticercosis.
This resected lesion came
from a seizure patient.
(Courtesy B. Cremin, MD.)
(Right) This section shows
a dead cysticercus with a
degenerating larvae. (Courtesy
Franz von Lichtenberg
Collection of ID Pathology,
BWH.)
V
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8
Microscopic Features
p
p
Helminthic Parasitic Infections: Cestodes
CYSTICERCOSIS
(Left) This section shows
a mononuclear infiltrate
surrounding a leaking
cysticercus. (Courtesy Franz
von Lichtenberg Collection
of ID Pathology, BWH.)
(Right) A higher power view
of a leaking cysticercus
highlights the syncytial cyst
membrane with underlying
cytons. (Courtesy Franz von
Lichtenberg Collection of ID
Pathology, BWH.)
(Left) This section shows
a multicystic, "racemose"
cysticercus. (Courtesy
Franz von Lichtenberg
Collection of ID Pathology,
BWH.) (Right) A higher
ower view of a multicystic,
"racemose" cysticercus
highlights the irregular
roliferation of the syncytial
membrane. (Courtesy Franz
von Lichtenberg Collection
of ID Pathology, BWH.)
(Left) This section shows
a scolex , gastrodermis
, and suckers of
a cysticercus of Taenia
solium. (Courtesy Franz von
Lichtenberg Collection of ID
Pathology, BWH.) (Right)
Inflammation surrounding a
"racemose" cysticercus can
be extensive. (Courtesy Franz
von Lichtenberg Collection
of ID Pathology, BWH.)
V
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SECTION 1
Invertebrates in Tissue
Myiasis VI-1-2
Scabies VI-1-4
Demodex Infestations VI-1-6
Tungiasis VI-1-8
MYIASIS
Cross sections of a botfly larva (unidentified) are shown,
which were taken from the skin of a patient who traveled
to Africa.
TERMINOLOGY
Synonyms
Flystrike, blowfly strike, fly-blown: Myiasis
Definitions
Greek: "Myia" (fly)
ETIOLOGY/PATHOGENESIS
Environmental Exposure
Poor hygiene and low socioeconomic status
Travel to endemic regions without proper precautions
Infestations and Other Invertebrate-Related Maladies: Direct Evidence of Invertebrates in Tissue
VI
Preexisting suppurative lesions that attract deposit of
eggs by Diptera flies
Infectious Agents
Infestation of human or animal tissue by fly larvae
(maggots) that can feed on host’s tissues, liquid body
substances, or ingested food
Species of maggots that feed only on dead tissue do
not typically cause myiasis (e.g., common house fly)
Diptera "2-winged true fly" are order of insects
responsible
150,000 species in 10,000 genera and 150 families (a
small subset cause myiasis)
Classified by: (1) taxonomic family, and (2)
differences in pathogenic behavior
Botflies (Dermatobia hominis), American warble fly
(torsalo): Southeastern Mexico to northern Argentina,
Chile, Uruguay
Screwworm, old world screwworm, Chrysomya: Asia,
Africa, India, Papua New Guinea
Blowflies, new world screwworm fly, Cochliomyia
hominivorax: Central and South America
Flesh flies, Sarcophagidae: Worldwide; cause myiasis
in sheep but also carry leprosy and cause intestinal
pseudomyiasis if ingested by humans
Higher magnification of the myiasis fly larva reveals the
cuticular spines. In addition, striated muscle in organisms
found in the skin is consistent with insect larvae or adults
.
Mango fly, tumbu fly, tumba fly, putzi fly, Cordylobia:
East and Central Africa
CLINICAL ISSUES
Epidemiology
Myiasis is among the 5 most common dermatologic
conditions in travelers, representing 7.3-11% of cases
Leprosy is endemic in countries where myiasis-causing
flies are highly prevalent
Presentation
Cutaneous myiasis and wound myiasis are the most
common forms
Furuncular myiasis occurs after penetration of larva
into skin
Papule or nodule with a central punctum, which
causes pruritus and pain
Number of larvae within lesion varies with
offending species
Dermatobia hominis, Cordylobia anthropophaga,
Cuterebra species, Wohlfahrtia vigil, and
Wohlfahrtia magnifica
Migratory myiasis occurs when a dipteran maggot
migrates through burrows in skin, producing
migratory "creeping" pattern
Larvae of Gasterophilus (horse botfly) and Hypoderma
(cattle botfly) cause this pattern in humans
Wound myiasis occurs when fly larvae infest open
wounds of host
Cochliomyia hominivorax, Chrysomya bezziana, and
W. magnifica are the most common flies for wound
myiasis
Cavitary myiasis corresponds to infection of body
cavities
Orbital myiasis, or ophthalmomyiasis profunde, is
infection of any anatomic structure of eye
1
2
Terminology
Infestation of human or animal tissue by fly larvae
(maggots) that can feed on host’s tissues, liquid body
substances, or ingested food
Etiology
Diptera "2-winged true fly" are order of insects
responsible
Other uncommon forms include ENT myiasis,
urogenital myiasis, intestinal myiasis, cerebral myiasis,
tracheopulmonary myiasis, and umbilical cord myiasis
Treatment
Surgical removal/debridement
Required for wound myiasis
May be primary approach for simple cutaneous
myiasis (requested by patient, not required)
Occlusion/oxygen depletions
Nonrestrictive cover (oil, animal fat, meat,
petroleum jelly) forces larvae to migrate for oxygen
supply
Emerges over a few hours and reduces scarring from
surgical removal
Alternative therapy (especially for oral or orbital)
Oral ivermectin or topical ivermectin
Prognosis
Self-limited disease in simple form (larvae is lost in 5-7
weeks)
Wound with debridement and management of
secondary infections is excellent
MICROBIOLOGY
Macroscopic Identification
Most parasitological laboratories can aid in visual
identification under magnification of larvae after
removal of intact maggot
MYIASIS
Key Facts
Clinical Issues
Among the 5 most common dermatologic conditions
in travelers, representing 7.3-11% of cases
Cutaneous myiasis and wound myiasis are the most
common forms
Top Differential Diagnoses
Cellulitis or furunculosis, and ruptured epidermoid
cyst
Leishmaniasis, onchocerciasis, or tungiasis
MICROSCOPIC PATHOLOGY
Histologic Features
Ulcerated epidermis hyperkeratosis; dermis contains
mixed acute and chronic inflammatory infiltrate
Dipteran larva is seen in cross section
Intact larvae inspected with magnification is sufficient
for diagnosis
DIFFERENTIAL DIAGNOSIS
Cellulitis or Furunculosis, and Ruptured
Epidermoid Cyst
Absence of larva or insect parts in tissue can rule out
myiasis
Leishmaniasis, Onchocerciasis, or Tungiasis
Myiasis larvae can be seen in cross section
SELECTED REFERENCES
1. Francesconi F et al: Myiasis. Clin Microbiol Rev.
2. Robbins K et al: Cutaneous myiasis: a review of the
3. Hakeem MJ et al: Exotic human myiasis. Travel Med Infect
Infestations and Other Invertebrate-Related Maladies: Direct Evidence of Invertebrates in Tissue
25(1):79-105, 2012
common types of myiasis. Int J Dermatol. 49(10):1092-8,
2010
Dis. 7(4):198-202, 2009
IMAGE GALLERY
(Left) Dermatobia hominis larva is shown. (Courtesy O. Lupi, MD, PhD.) (Center) Many large C. hominivorax larvae are shown in a basal cell
carcinoma case. (Courtesy O. Lupi, MD, PhD.) (Right) This image shows myiasis due to C. hominivorax in a B-cell lymphoma patient. Shown is a
huge ulcer filled with larvae. (Courtesy O. Lupi, MD, PhD.)
VI
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SCABIES
Scabies presented in this patient as multiple, excoriated
papules and burrows on the hand. (From DP:
Nonneoplastic Derm.)
TERMINOLOGY
Synonyms
7-year itch
Crusted scabies (Norwegian scabies)
Definitions
Latin: "Scabere" (to scratch)
ETIOLOGY/PATHOGENESIS
Environmental Exposure
Considered a water-related disease (WHO)
Infestations and Other Invertebrate-Related Maladies: Direct Evidence of Invertebrates in Tissue
Spread via contact with infected person (most
contagious) or objects in contact with infected person
Infectious Agents
Sarcoptes scabei var. hominis
Acquired ectoparasite infestation involving skin
Mites of 0.5 mm (appear as small white spots)
Highly contagious via direct skin-to-skin contact
and less frequently via fomites such as bedding or
clothing
Norwegian scabies is characterized by crusted lesions
and scaly plaques infected with hundreds to millions
of female mites. (Courtesy R. Alarcon, MD.)
Nodular scabies
Subcutaneous nodules
Predilection for lower trunk, thighs, and scrotum
More prevalent in young/pediatric populations
Norwegian/crusted scabies
Diffuse epidermal crusts
Extremely high mite load
More prevalent in immunocompromised and
debilitated populations
Treatment
Drugs
Topical permethrin or oral ivermectin
Prognosis
With appropriate treatment, resolves with little
scarring
Recurrence may occur from close contacts (require
treatment)
Crusted scabies requires a prolonged course of therapy
and may be difficult to eradicate
Thorough environmental cleaning may be required
MACROSCOPIC FEATURES
VI
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CLINICAL ISSUES
Epidemiology
Incidence
100 million affected people worldwide (most
common in children)
Presentation
Intense pruritis with nocturnal worsening
Classical scabies
Burrows: Wavy gray-brown lines on epidermal
surface
Predilection for palms, soles, wrists, nipples,
inframammary folds, waist, and male genitalia
Skin
Linear or curved burrows appear red and possibly
excoriated
MICROSCOPIC PATHOLOGY
Histologic Features
Epidermal intracorneal presence of female scabies
mite, eggs, or feces (scybala) is pathognomonic
Ovoid mite is 0.3-0.4 mm in length
Chitinous exoskeleton
4 pairs of legs: 2 pair anterior, 2 pair lateral
Dorsal spines
Classical scabies
Etiology
Spread via contact with infected person (most
contagious) or objects in contact with infected person
Clinical Issues
100 million affected people worldwide (most
common in children)
Burrows: Wavy gray-brown lines on epidermal surface
Classical scabies
Intracorneal mites typically found at edge of
cutaneous burrow
Associated nonspecific inflammatory response
Superficial and deep perivascular and interstitial
dermal lymphocytic infiltrate with numerous
eosinophils
epidermal spongiosis
subcorneal vesicles containing numerous
eosinophils
Nodular scabies
Histologic identification of mites is less common
Dense superficial and deep dermal
lymphohistiocytic infiltrate with numerous
eosinophils
Norwegian/crusted scabies
Psoriasiform hyperplasia
Massive epidermal hyperkeratosis and parakeratosis
Abundant mites
Multilayered burrows
DIFFERENTIAL DIAGNOSIS
Arthropod Bite
Dermatitis with neutrophils, eosinophils, and
lymphocytes with a more prominent perivascular
distribution at early stages
Older lesions may show diffuse or nodular
inflammation
Endothelial swelling
Rarely, insect mouth parts are identified in dermis
SCABIES
Key Facts
Predilection for palms, soles, wrists, nipples,
inframammary folds, waist, and male genitalia
Norwegian/crusted scabies
More prevalent in immunocompromised and
debilitated populations
Microscopic Pathology
Identification of scabies mites, eggs, or scybala
in subcorneum or superficial epidermis is
pathognomonic
Eczematous Dermatitis
Exuberant dermatitis may be difficult to differentiate
in absence of scabies mites, eggs, or scybala
Cutaneous Larva Migrans
Similar spongiotic and perivascular chronic dermatitis
with numerous eosinophils
Rarely identified nematode larval forms 0.5 mm thick
and up to 10 mm long in deep dermis
DIAGNOSTIC CHECKLIST
Pathologic Interpretation Pearls
For high clinical suspicion in absence of
pathognomonic mites, eggs, or scybala, deeper
histologic levels or repeat biopsy may be warranted for
definitive diagnosis
SELECTED REFERENCES
1. Mounsey KE et al: Scratching the itch: new tools to
2. Shmidt E et al: Dermatologic infestations. Int J Dermatol.
3. Walton SF et al: Problems in diagnosing scabies, a global
Infestations and Other Invertebrate-Related Maladies: Direct Evidence of Invertebrates in Tissue
advance understanding of scabies. Trends Parasitol.
29(1):35-42, 2013
51(2):131-41, 2012
disease in human and animal populations. Clin Microbiol
Rev. 20(2):268-79, 2007
MICROSCOPIC FEATURES
(Left) A gravid female Sarcoptes mite displaying typical chitinous exoskeleton and dorsal spines is present in a subcorneal burrow. Adjacent
to the mite are 2 Sarcoptes eggs
infiltrate. Papillary dermal edema is present
to florid eczematous dermatitis.
. (Center) Scabies infestations frequently show a superficial/deep perivascular lymphocytic/eosinophilic
. (Right) Florid superficial and perivascular dermatitis with numerous eosinophils is shown, similar
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DEMODEX INFESTATIONS
H&E stained skin biopsy shows a dense inflammatory
infiltrate around sebaceous gland, and Demodex
mites .
TERMINOLOGY
Synonyms
Demodicosis
Demodectic mange, red mange (in canids)
Demodicidosis
Definitions
Greek: "Demos" (tallow) + "dex" (woodworm)
ETIOLOGY/PATHOGENESIS
Environmental Exposure
Infestations and Other Invertebrate-Related Maladies: Direct Evidence of Invertebrates in Tissue
Worldwide distribution, very common to find on
human skin
No racial or sex predilections have been observed
Infectious Agents
Demodex is name given to small mites that live in hair
follicles; condition is called demodicosis
2 species: Demodex folliculorum (DF) and Demodex
brevis
D. folliculorum (all stages) is found in small hair
follicles and eyelash hair follicles
D. brevis (all stages) is present in eyelash sebaceous
glands, small hair sebaceous glands, and lobules of
meibomian glands
Life cycle of D. folliculorum estimated to be only 14.5
days from ovum to adult stage
Cross section of skin biopsy stained with H&E shows
Demodex mites .
Presentation
Very frequently are simply incidental findings, which
are unrelated to underlying pathology generating a
biopsy
Demodicidosis
Pruritic, erythematous, papulopustular lesions
Variations include pityriasis folliculorum, rosacealike demodicidosis, or demodicidosis gravis
Madarosis (loss of lashes) is associated with heavy
infestation by mites
Demodex species-induced pathologic changes can
cause dry eye conditions and chalazia formation
Demodex blepharitis: Ocular irritation, itching, and
scaling of lids
Rosacea: Number of Demodex mites in rosacea patients
higher than in control subjects
Demodex can proliferate in immunodeficiency states
such as human immunodeficiency virus (HIV)
infection
Treatment
Tea tree oil with Macadamia nut oil are commonly
used
Topical insecticides in heavy infestation
Oral ivermectin in severe cases, e.g., HIV patients
Prognosis
No major morbidity or mortality
MACROSCOPIC FEATURES
VI
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CLINICAL ISSUES
Epidemiology
Prevalence of Demodex spp. infestation in 1 recent
study was 41% and was highest among inpatients and
elderly
In general population, age 20-30 has highest
colonization due to rate of sebum production
General Features
D. folliculorum measures 0.3-0.4 mm in length,
whereas D. brevis measures 0.15-0.2 mm with similar
structure of head and thorax but shorter abdomen
DEMODEX INFESTATIONS
Terminology
Demodex is name given to small mites that live in hair
follicles; condition is called demodicosis
Clinical Issues
Demodex species-induced pathologic changes can
cause dry eye conditions, chalazia formation, and
play important role in pityriasis folliculorum
Rosacea: Number of mites in rosacea patients higher
than in control subjects
Key Facts
Microscopic Pathology
Demodex folliculorum adult and immature forms
consume epithelial cells, cause follicular hyperplasia
and marked keratinization
Top Differential Diagnoses
Chalazion, blepharitis, and dry eye syndrome
Infestations and Other Invertebrate-Related Maladies: Direct Evidence of Invertebrates in Tissue
MICROSCOPIC PATHOLOGY
Histologic Features
Demodicidosis show papulopustular lesions with
neutrophils in/around glands with organisms
D. folliculorum adult and immature forms consume
epithelial cells and cause follicular hyperplasia and
marked keratinization
D. brevis adult and immature forms consume
sebaceous and meibomian gland cells when
infestations are heavy
Both mites produce inflammatory changes, epithelial
hyperplasia, and follicular plugging
Organisms are mites and have chitin exoskeleton
DIFFERENTIAL DIAGNOSIS
Chalazion
Granulomatous inflammation of meibomian glands,
composed of epithelioid cells and histocytes and
chronic inflammation; no mites present in biopsy
Demodicidosis should be considered in adults
presenting with recurrent chalazia
Blepharitis
Caused by bacterial colonization of eyelid
Dry Eye Syndrome
Multifactorial disease of tears and ocular surface that
causes discomfort and tear film instability; no mites
present in histological section
Scabies
Burrow through skin, not usually on face; mites in
epidermis (not gland associated)
SELECTED REFERENCES
1. Chen W et al: Human demodicosis: revisit and a proposed
classification. Br J Dermatol. 170(6):1219-25, 2014
2. Elston CA et al: Demodex mites. Clin Dermatol.
32(6):739-43, 2014
3.
Rusiecka-Zikowska J et al: Demodex - an old pathogen or
a new one? Adv Clin Exp Med. 23(2):295-8, 2014
4. Wesolowska M et al: Prevalence of Demodex spp. in
eyelash follicles in different populations. Arch Med Sci.
10(2):319-24, 2014
5. Zhao YE et al: Sequencing for complete rDNA sequences
(18S, ITS1, 5.8S, ITS2, and 28S rDNA) of Demodex and
phylogenetic analysis of Acari based on 18S and 28S rDNA.
Parasitol Res. 111(5):2109-14, 2012
6. Kligman AM et al: Demodex folliculorum: requirements
for understanding its role in human skin disease. J Invest
Dermatol. 131(1):8-10, 2011
7. Moravvej H et al: Association of rosacea with demodicosis.
Arch Iran Med. 10(2):199-203, 2007
8. Gao YY et al: In vitro and in vivo killing of ocular
Demodex by tea tree oil. Br J Ophthalmol. 89(11):1468-73,
2005
IMAGE GALLERY
(Left) H&E section shows mild to moderate chronic inflammation around sebaceous glands. Demodex mites are visible . (Center) High-power
view shows cross section of Demodex folliculorum
biopsy of facial skin, consistent with Demodex sp.
in a skin biopsy stained with H&E. (Right) Hair follicle is distended with many mites in a
.
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