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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_182_библиотеки_им_акад_М_И_Перельмана.pdf
PNEUMOCYSTOSIS
A bronchial washing with GMS stain demonstrates round
to boat-shaped cysts with nuclei adjacent to the
cell wall . (Courtesy R. Brynes, CDC/PHIL.)
Fungal Infections: Morphological Diagnosis of Fungal Infections
TERMINOLOGY
Definitions
Pneumocystis: New Latin and Greek: "Pneumo" (breath)
and Latin: "Cystis" (anatomical sac)
jiroveci: Named after Otto Jirovec, who first described
Pneumocystis pneumonia (PCP) in humans in 1952
ETIOLOGY/PATHOGENESIS
Environmental Exposure
Ubiquitous airborne organisms in environment lead to
colonization and infection
Infectious Agents
Pneumocystis jiroveci (formerly, Pneumocystis carinii)
Yeast-like fungus with poorly understood life cycle
and limited genomic data (cannot be grown in
culture)
CLINICAL ISSUES
P. jiroveci cysts are demonstrated in a bronchoalveolar
lavage with immunofluorescence assay. (Courtesy W.
Pieciak, Jr. SM[ASCP].)
Site
Lungs (alveoli)
Extrapulmonary (lymph nodes, spleen, bone marrow)
infection in < 3% of cases
Presentation
Dyspnea, dry cough, fever, usually of > 4 weeks
duration in patients with HIV
Low oxygen saturations are present, especially in those
without HIV
Laboratory Tests
Identification of P. jiroveci is performed on bronchial
secretions (induced sputum or bronchoalveolar lavage
[BAL], or rarely on tissue samples
Immunofluorescence assay is gold standard for
diagnosis
Serum (13)--D-glucan can be elevated, found to be
92% sensitive and 65% specific for PCP infection
Natural History
Primarily moderate to severe pulmonary disease in
immunocompromised, with rare dissemination
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Epidemiology
Worldwide distribution
Most individuals have been exposed by age 4
Opportunistic disease, occurring in
immunocompromised patients
HIV infection, mainly in setting of a CD4 Tcell count < 200 cells/mm, other coexisting
opportunistic infections, unintentional weight loss,
and high viral load
Immunodeficient patients (primary
immunodeficiencies, post renal transplant,
hematopoietic malignancies, and use of TNF
inhibitors)
Malnourished &/or premature children (seen during
World War II)
Treatment
Trimethoprim-sulfamethoxazole, pentamidine,
dapsone, atovaquone
Prognosis
Mortality rate: 10-20% in those with HIV
Mortality rate: 20-50% in those without HIV
IMAGE FINDINGS
Radiographic Findings
"Bat wing" appearance on chest x-ray of diffuse
bilateral perihilar infiltrates
Ground-glass opacities
PNEUMOCYSTOSIS
Terminology
PCP pneumonia
Etiology
Pneumocystis jiroveci is a ubiquitous organism causing
opportunistic disease, associated with HIV infection,
immunodeficiencies, and malnourishment
Clinical Issues
Presents with dyspnea, dry cough, fever, usually of >
4 weeks duration in patients with HIV
Mortality rate: 10-20% in those with HIV, 20-50% in
those without HIV
Classified as a member of ascomycetous fungi,
existing in 2 forms: Asexual trophic form (1-4 m)
and sexually reproductive cystic forms (8 m)
Cannot be cultured in vitro
Differential of ground-glass opacities is broad,
and often opportunistic infections can have this
appearance
Other infectious causes to consider include CMV,
HSV, and RSV
Key Facts
Imaging Findings
"Bat wing" appearance on chest x-ray of diffuse
bilateral perihilar infiltrates
Microscopic Pathology
Grocott methenamine silver stain shows uniformly
sized trophic forms (4 m), spherical or boat-shaped
Accumulation of intraalveolar eosinophilic foamy
proteinaceous material
Limited interstitial plasma cell-rich inflammation
Top Differential Diagnoses
Adult respiratory distress syndrome, pulmonary
embolism
Tuberculosis, legionellosis, Mycoplasma disease,
mycobacterial disease, influenza
DIFFERENTIAL DIAGNOSIS
Noninfectious
Adult respiratory distress syndrome, pulmonary
embolism
Fungal Infections: Morphological Diagnosis of Fungal Infections
MICROBIOLOGY
Fungal Features
Exists in 2 forms: Asexual trophic form (1-4 m in
diameter) and sexually reproductive cystic forms (8
m in diameter)
Trophic forms are most abundant form present
during Pneumocystis pneumonia infection (10:1)
MICROSCOPIC PATHOLOGY
Histologic Features
Grocott methenamine silver stain shows uniformly
sized trophic forms (4 m), spherical or boat-shaped
Nuclei are frequently adjacent to cell wall
Accumulation of intraalveolar eosinophilic foamy
proteinaceous material
Limited interstitial plasma cell-rich inflammation
Cytologic Features
Organisms seen with Grocott methenamine silver
stain of bronchial washings, boat-shaped or "crushed
ping-pong balls"
ANCILLARY TESTS
Immunofluorescence
Detects P. jiroveci cysts with greater sensitivity than
silver staining and is gold standard for sputum and
bronchoalveolar lavage testing
Infectious
Tuberculosis, Mycobacterium avium complex (MAC)
Positive AFB stain or mycobacterial culture
Necrotizing granuloma formation
Legionella and Mycoplasma infections
Legionella infection results in lobar pneumonia,
small vessel vasculitis, neutrophilic infiltrate,
coagulation necrosis, and focal septal disruption
Mycoplasma infection results in a neutrophilic-rich
bronchiolar exudate and peribronchiolar septal
widening
Influenza
Necrotizing tracheobronchitis, diffuse alveolar
damage
DIAGNOSTIC CHECKLIST
Clinically Relevant Pathologic Features
One of the most common opportunistic infections
seen with HIV
Presents with dyspnea, dry cough, and fever
Pathologic Interpretation Pearls
Immunofluorescence is gold standard for detection
(nonculturable)
Characteristic eosinophilic foamy plugging in alveolar
spaces
SELECTED REFERENCES
1. Thomas CF Jr et al: Current insights into the biology
and pathogenesis of Pneumocystis pneumonia. Nat Rev
Microbiol. 5(4):298-308, 2007
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Microscopic Features
(Left) Eosinophilic foamy
alveolar plugging is
shown with a plasma cell
inflammatory infiltrate
. (Courtesy Franz von
Lichtenberg Collection of
Infectious Disease Pathology,
BWH.) (Right) Extensive
alveolar plugging with
eosinophilic exudate is
demonstrated in the lung of
an infected patient. (Courtesy
Franz von Lichtenberg
Collection of Infectious
Disease Pathology, BWH.)
Fungal Infections: Morphological Diagnosis of Fungal Infections
(Left) Eosinophilic foamy
alveolar plugging and
interstitial infiltrates
are shown in the lung of
an infected patient. Note
the prominent interstitial
inflammatory response,
which is atypical. (Courtesy
Franz von Lichtenberg
Collection of Infectious
Disease Pathology, BWH.)
(Right) Grocott methenamine
silver stain demonstrates
trophic forms (4 m) with a
boat or crushed ping-pong
ball shape . (Courtesy Franz
von Lichtenberg Collection of
Infectious Disease Pathology,
BWH.)
PNEUMOCYSTOSIS
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(Left) The typical appearance
of the lung in P. jiroveci
infection is eosinophilic
alveolar foamy plugging
and a limited interstitial
inflammatory response.
(Courtesy Franz von
Lichtenberg Collection of
Infectious Disease Pathology,
BWH.) (Right) Grocott
methenamine silver stain
demonstrates P. jiroveci
organisms in the alveolus
of a lung.
Microscopic Features
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p
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Fungal Infections: Morphological Diagnosis of Fungal Infections
PNEUMOCYSTOSIS
(Left) A lung section is
shown from a case of
disseminated P. jiroveci
infection. The alveolar
spaces are empty except for
the presence of P. jiroveci
organisms as seen on
this GMS stain. (Courtesy
Franz von Lichtenberg
Collection of Infectious
Disease Pathology, BWH.)
(Right) Disseminated
neumocystosis is
demonstrated involving the
kidney glomerulus. (Courtesy
Franz von Lichtenberg
Collection of Infectious
Disease Pathology, BWH.)
(Left) Disseminated
neumocystosis is shown
involving the thyroid gland
with clusters of cysts
. (Courtesy Franz von
Lichtenberg Collection of
Infectious Disease Pathology,
BWH.) (Right) Disseminated
neumocystosis involving the
liver shows a foamy mass of
artially calcified organisms
causing inflammation
. (Courtesy Franz von
Lichtenberg Collection of
Infectious Disease Pathology,
BWH.)
(Left) Coinfection with
cytomegalovirus and
P. jiroveci is shown with
an eosinophilic foamy
lugging of alveoli typical
of P. jiroveci . (Courtesy
Franz von Lichtenberg
Collection of Infectious
Disease Pathology, BWH.)
(Right) Electron microscopy
demonstrates the boatshaped P. jiroveci cell .
The membranotubular
extensions contribute
to the alveolar infiltrate.
(Courtesy Franz von
Lichtenberg Collection of
Infectious Disease Pathology,
BWH.)
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SPOROTRICHOSIS
An isolated lesion of sporotrichosis on the left thumb
demonstrates ulceration , induration , and adjacent
inflammation . (Courtesy K. Gardiner.)
Fungal Infections: Morphological Diagnosis of Fungal Infections
TERMINOLOGY
Synonyms
Rose-thorn or rose-gardener’s disease
Definitions
Greek: "Spora" (seed) + "thrix" (hair)
"schenckii" from Benjamin Schenck, who first isolated
the fungus from a patient
ETIOLOGY/PATHOGENESIS
Environmental Exposure
Direct inoculation into skin or inhalation of fungus
From plants (roses)
Mosses, hay, and oil (farmers)
In cats (veterinary/owner risk)
Infectious Agents
Complex of fungal species previously grouped under
one main species, Sporothrix schenckii
Sporothrix brasiliensis
Sporothrix albicans
Sporothrix globosa
Sporothrix inflata
Sporothrix mexicana
Sporothrix schenckii var. luriei
Thermally dimorphic fungi found as yeast at 37 C
and mycelium at room temperature
CLINICAL ISSUES
Epidemiology
Worldwide distribution of fungus
No racial or gender predilections
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Presentation
Sporotrichosis of skin
1
Sporotrichosis (forearm) shows ulcerative spread
up lymphatic channels . The pattern, called
"sporotrichoid," can be seen in other diseases (e.g.,
leishmaniasis, mycobacteria).
Initial inoculation (distal extremities)
Small entry site lesions (1 week to several months)
Enlarge in size, discolored (dark red to purple)
with crusting, "boils"
New nodule(s)
Proximal to initial lesion
Spread along lymphatics beginning 2 weeks after
initial lesion
Ulceration of any lesion can occur with risk of
secondary bacterial infection
Sporotrichosis of lungs
Inhalational exposure with cough and lesions on
chest x-ray
Chronic disease
Fibrosis, large nodules cavitation, and hilar
adenopathy
Secondary infections including bacterial
pneumonia, atypical mycobacterial infections, and
tuberculosis
Disseminated sporotrichosis
Spread to other organs (especially bone &/or brain)
occurs with anorexia
More common in immunosuppressed patients
Laboratory Tests
Serological evidence of exposure (IgG)
Culture of lesions (skin), sputum (pulmonary),
cerebrospinal fluid (disseminated), or joint/bone
aspirates (disseminated)
Treatment
Surgical approaches
Deep mycoses (e.g., lung nodules, bone
involvement) may require surgical removal
Drugs
Skin
Topical antifungals (potassium iodide)
Pulmonary or disseminated
Itraconazole, posaconazole, &/or amphotericin B
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SPOROTRICHOSIS
Etiology
Sporothrix schenckii and subspecies: Thermally
dimorphic fungi
Plants (roses); mosses, hay, and oil (farmers); and on
animals (veterinary risk)
Clinical Issues
Skin
Begin as small inoculation site lesions that enlarge
in size, become discolored (dark red to purple) with
crusting, "boils"
Lungs
Inhalational exposure with cough and lesions on
chest x-ray
Chronic disease: Fibrosis, large nodules
cavitation, and hilar adenopathy
Prognosis
Most patients recover with antifungal treatment
Immunosuppressed patients with disseminated disease
have worse prognosis
Key Facts
Microscopic Pathology
Mixed neutrophilic and granulomatous lesions with
round to oval yeast, demonstrate budding, or show
"teardrop" configuration
Ancillary Tests
28S rRNA for genus and calmodulin gene for species
Top Differential Diagnoses
Tuberculosis, Mycobacterium marinum infection,
leprosy, cat scratch disease, syphilis, sarcoidosis
Diagnostic Checklist
Sporotrichoid pattern of nodules on extremity should
elicit thorough work-up for organisms
Teardrop cells &/or yeast with Splendore-Hoeppli
phenomenon are useful but not always present
Yeast forms
Splendore-Hoeppli phenomenon
Fungal Infections: Morphological Diagnosis of Fungal Infections
Round to oval, demonstrate budding or show
"teardrop" configuration
Crystalline host proteins surrounding yeast
MICROBIOLOGY
Culture
Rapidly maturing colonies are produced within 5 days
Some variation in rates of maturity among different
species
Malt extract agar or potato dextrose agar yield
smooth/wrinkled colonies that go from white to black
Growth at 25 C yields mycelium including dark cell
walled conidia, which distinguish Sporothrix from
other species
Brain-heart infusion agar for transition from mold to
yeast, Sabouraud dextrose agar to maintain yeast
Growth at 37 C yields yeast forms that are similar
in appearance to tissue forms
Assimilation of sucrose, raffinose, and ribitol can assist
with speciation
MACROSCOPIC FEATURES
Skin Lesions
Nodules may be large, indurated, crusting, or ulcerated
and may appear in linear fashion on extremity
(sporotrichoid growth pattern)
"Sporotrichoid" is often used by dermatologist but
may refer to several diseases (i.e., not specific for
sporotrichosis)
MICROSCOPIC PATHOLOGY
Histologic Features
Mixed neutrophilic and granulomatous lesions (all
sites)
Plasma cells in chronic lesions
ANCILLARY TESTS
PCR
28S rRNA PCR and sequencing can distinguish
Sporothrix from other fungi
Calmodulin gene can separate species of Sporothrix
DIFFERENTIAL DIAGNOSIS
DDx of Skin Lesions
Tuberculosis, Mycobacterium marinum infection, leprosy
Granulomatous lesions with necrosis lacking
neutrophils or plasma cells
AFB-positive organisms
Syphilis
Dense plasma cell infiltrates without granulomas
Spirochetes on silver stain or
immunohistochemistry
Leishmaniasis
Macrophages filled with organisms showing a "dotdash" (nucleus-kinetoplast) appearance
Giemsa stains highlight the organisms
Sarcoidosis
Lack of yeast forms
Less suppurative
More granulomatous (without necrosis)
Malignancy
Ulceration may disrupt upper layers of tumor
Malignant cells with mitoses, pleomorphism, and
invasion
DDx of Pulmonary Disease
Tuberculosis
AFB-positive organisms
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SPOROTRICHOSIS
Sugar Assimilation and Colony Size
Species (Cl) Sucrose/Raffinose/Ribitol (%)
S. brasiliensis (I) 0/0/19
S. schenckii (IIa) 100/100/100
S. schenckii (IIb) 100/100/33
S. globosa (III) 100/0/91
S. mexicana (IV) 100/100/100
S. albicans (V) 100/0/50
The pattern of sugar assimilation by fungus in culture as well as the relative sizes of the colonies at various temperatures is shown for the species representing the 6 clades of Sporothrix. The
clades (Cl) are based on molecular analysis of the calmodulin gene. (Adapted from Marimon R et al, 2007.)
Tularemia
Gram-negative rods, history of exposure, serological
testing, PCR to confirm
DDx of Disseminated Disease
Melioidosis
Burkholderia pseudomallei (Gram-negative rods)
History of exposure
Serological testing, PCR or culture to confirm
Fungal Infections: Morphological Diagnosis of Fungal Infections
Cat scratch disease
Bartonella henselae (Warthin-Starry staining
organisms)
Involves lymph nodes (uncommon in
sporotrichosis)
Serological testing, PCR to confirm
DIAGNOSTIC CHECKLIST
Clinically Relevant Pathologic Features
Sporotrichoid pattern of nodules on extremity should
elicit thorough work-up for organisms
Pathologic Interpretation Pearls
Teardrop cells &/or yeast with Splendore-Hoeppli
phenomenon are useful but not always present
SELECTED REFERENCES
1. de C Negrini T et al: Influence of TLR-2 in the immune
response in the infection induced by fungus Sporothrix
schenckii. Immunol Invest. 43(4):370-90, 2014
2. Trotter JR et al: Sporothrix schenckii lymphadentitis in a
male with X-linked chronic granulomatous disease. J Clin
Immunol. 34(1):49-52, 2014
3. Zhang Y et al: Cancer-like lesions in a patient with
sporotrichosis. Int J Dermatol. 53(4):e311-2, 2014
4. Aung AK et al: Pulmonary sporotrichosis: case series and
systematic analysis of literature on clinico-radiological
patterns and management outcomes. Med Mycol.
51(5):534-44, 2013
5. Chang S et al: Disseminated cutaneous sporotrichosis.
Dermatol Online J. 19(11):20401, 2013
6.
Fernndez-Silva F et al: Virulence of Sporothrix luriei in a
murine model of disseminated infection. Mycopathologia.
173(4):245-9, 2012
7.
Vsquez-del-Mercado E et al: Sporotrichosis. Clin
Dermatol. 30(4):437-43, 2012
8. Rees RK et al: Feline-transmitted sporotrichosis: A case
III
study from California. Dermatol Online J. 17(6):2, 2011
At 20, 30, 35, and 37 C (mm SD)
25 6, 25 6, 17 7, 8 2
29 5, 36 6, 21 7, 6 3
30 3, 34 3, 21 4, 6 2
29 7, 31 5, 12 5, < 1
54 1, 68 2, 11 1, 2 1
51 3, 67 4, 28 1, 4 1
9. Yap FB: Disseminated cutaneous sporotrichosis in
an immunocompetent individual. Int J Infect Dis.
15(10):e727-9, 2011
10. Zhang YQ et al: Sporotrichosis: clinical and
histopathological manifestations. Am J Dermatopathol.
33(3):296-302, 2011
11. Zhang Z et al: Variation in genotype and higher virulence
of a strain of Sporothrix schenckii causing disseminated
cutaneous sporotrichosis. Mycopathologia. 172(6):439-46,
2011
12. Daniel Da Rosa W et al: Asteroid body in sporotrichosis.
Yeast viability and biological significance within the host
immune response. Med Mycol. 46(5):443-8, 2008
13. Gerhard R et al: Fine-needle aspiration biopsy of
disseminated sporotrichosis: a case report. Diagn
Cytopathol. 36(3):174-7, 2008
14. Xavier MH et al: Cat-transmitted cutaneous lymphatic
sporothricosis. Dermatol Online J. 14(7):4, 2008
15. Marimon R et al: Sporothrix brasiliensis, S. globosa, and S.
mexicana, three new Sporothrix species of clinical interest.
J Clin Microbiol. 45(10):3198-206, 2007
16. Silva-Vergara ML et al: Multifocal sporotrichosis with
meningeal involvement in a patient with AIDS. Med
Mycol. 43(2):187-90, 2005
17. de Lima Barros MB et al: Sporotrichosis with widespread
cutaneous lesions: report of 24 cases related to
transmission by domestic cats in Rio de Janeiro, Brazil. Int J
Dermatol. 42(9):677-81, 2003
18. Fleury RN et al: Zoonotic sporotrichosis. Transmission to
humans by infected domestic cat scratching: report of four
cases in So Paulo, Brazil. Int J Dermatol. 40(5):318-22,
2001
19. Ware AJ et al: Disseminated sporotrichosis with extensive
cutaneous involvement in a patient with AIDS. J Am Acad
Dermatol. 40(2 Pt 2):350-5, 1999
20.
Rodrguez G et al: The asteroid bodies of sporotrichosis.
Am J Dermatopathol. 20(3):246-9, 1998
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Gross and Microscopic
SPOROTRICHOSIS
(Left) Sporotrichosis of
the thumb demonstrates a
central ulcer
by a large area of discolored,
indurated tissue
the discoloration of the base
of the thumb compared
with the rest of the hand,
consistent with swelling and
inflammation. (Courtesy
K. Gardiner.) (Right) H&E
shows low magnification of
the skin in sporotrichosis
with prominent inflammation
.
surrounded
. Note
Fungal Infections: Morphological Diagnosis of Fungal Infections
(Left) H&E shows
sporotrichosis in the skin
with neutrophils and
eosinophils , epithelioid
histiocytes , giant cells
, and plasma cells .
The chronicity of the lesion,
spread via lymphatics, and
acute response lead to a
mixed inflammatory pattern.
(Right) High magnification
on H&E demonstrates a giant
cell containing a small
round yeast , consistent
with sporotrichosis.
(Left) High magnification of
sporotrichosis shows yeast
forms within a large
multinucleated giant cell.
(Courtesy L. Thompson,
MD.) (Right) PAS stain
highlights a fungal yeast
in a large giant cell. Asteroid
bodies (large eosinophilic
crystals around a yeast form)
can be helpful, but are not
always present and occur in
noninfectious lesions (e.g.,
sarcoidosis).
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TINEASIS
There is an erythematous, scaly plaque with
lichenification on the neck and jawline of this patient.
KOH examination of the scale showed fungal hyphae.
(From DP: Nonneoplastic Derm.)
Fungal Infections: Morphological Diagnosis of Fungal Infections
TERMINOLOGY
Definitions
Latin: "tinea" (worm)
Manifestations
Ringworm, tinea corporis, tinea capitis, tinea faciei,
tinea barbae, tinea cruris (jock itch), tinea unguium
(onychomycosis), tinea gladiatorum, tinea imbricata,
tinea manuum, tinea pedis (athlete’s foot), tinea
incognito
Nodular granulomatous perifolliculitis (Majocchi
granuloma)
ETIOLOGY/PATHOGENESIS
Environmental Exposure
Acquired by contact
Anthropophilic organisms: With infected humans
Zoophilic organisms: With infected animals
Geophilic organisms: With contaminated soil or
fomites
Infectious Agents
Superficial fungal infection of skin and skin
appendages
3 species of dermatophytes (aerobic fungi):
Trichophyton, Microsporum, and Epidermophyton
CLINICAL ISSUES
Epidemiology
Incidence
Affects 20-25% of world population
Immunocompromised states (HIV, diabetes, etc.)
III
associated with increased risk and dissemination
In this example of tinea corporis, PAS-D stain highlights
fungal hyphae in the stratum corneum of the
epidermis. There is coincident mild parakeratosis,
acanthosis, and inflammation.
Presentation
Tinea corporis (ring worm)
Itchy, annular patch or plaque of erythema with
scale at advancing edge and central clearing
Tinea Pedis (athlete’s foot)
Pruritus, erythema, scale, vesicles and pustules
Commonly centered on interdigital clefts
Tinea capitis
Scaly scalp, alopecia, pustules, and "black dots"
representing hairs broken at scalp
Tinea unguium (onychomycosis)
Causes nail dystrophy: Brittle, splitting, peeling,
weak
Candida and nondermatophyte fungal infections are
other causes of onychomycosis
Risk factors: Tinea pedis, improperly fitting shoes,
diabetes
Majocchi granuloma
Erythematous coalescing papules and pustules
Tinea incognito
Tinea imbricata
Multiple concentric annular plaques with thick rims
of peripheral scale
Tinea gladiotorum
Lesion morphology may resemble tinea corporis
Alternatively, may cause numerous erythematous
scaling papules and plaques
Tinea cruris (jock itch)
Pruritic, burning red symmetric macules with welldemarcated borders and pustules/vesicles at the edge
Disseminated dermatophytosis
In severely immunosuppressed patients,
hematogenous spread may cause signs/symptoms in
any organ
Laboratory Tests
In-office potassium hydroxide preparation of scrapings
is 77% sensitive
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Etiology
Superficial fungal infections of skin and skin
appendages
Acquired by contact
Clinical Issues
Multiple clinical forms are present
Classified by body site and etiology
Affects 20-25% of world population
Common in children
TINEASIS
Key Facts
Immunocompromised state increases risk including
dissemination
Microscopic Pathology
Fungal hyphae may be difficult to appreciate on H&E
Nonspecific changes in skin: Parakeratosis,
acanthosis/psoriasiform hyperplasia, inflammation
Ancillary Tests
Fungal hyphae positive for PAS-D and GMS
Fungal Infections: Morphological Diagnosis of Fungal Infections
Treatment
Topical or oral antifungals
Prognosis
Most clinical forms are responsive to therapy
Disseminated dermatophytosis may be severe and lead
to fatalities
MICROSCOPIC PATHOLOGY
Histologic Features
Cutaneous disease
Hyperkeratosis, parakeratosis, acanthosis/
psoriasiform hyperplasia
Neutrophils in stratum corneum
Fungal hyphae in stratum corneum of epidermis,
hair shaft, hair follicle, or nail matrix (difficult on
H&E stain)
Variable dermal mixed inflammatory infiltrate and
spongiosis
Disseminated disease
Neutrophilic, granulomatous, or necrotizing
inflammation with fungal hyphae
ANCILLARY TESTS
Histochemistry
Fungal forms are positive for PAS-D and GMS
histochemical stains
DIFFERENTIAL DIAGNOSIS
Spongiotic/Eczematous Processes
May show similar reactive changes (acanthosis,
hyperkeratosis)
PAS or GMS-positive organisms are not present
Disseminated Fungal Infection
Morphologically similar to hyalohyphomycoses and
candidiasis requiring culture to differentiate
DIAGNOSTIC CHECKLIST
Clinically Relevant Pathologic Features
Localized skin disease predominantly except in case of
severely immunosuppressed patients, where invasion
and dissemination can occur
Pathologic Interpretation Pearls
Dermatophyte infection must be ruled out prior to
diagnosis of most spongiotic/eczematous dermatitides
SELECTED REFERENCES
1. Laniosz V et al: What’s new in the treatment and diagnosis
of dermatophytosis? Semin Cutan Med Surg. 33(3):136-9,
2014
2. Kelly BP: Superficial fungal infections. Pediatr Rev.
33(4):e22-37, 2012
3. Ameen M: Epidemiology of superficial fungal infections.
Clin Dermatol. 28(2):197-201, 2010
IMAGE GALLERY
(Left) Potassium hydroxide (KOH) examination of scale from a dermatophyte infection of the skin will show branching hyphae . (From DP:
Nonneoplastic Derm.) (Center) In Majocchi granuloma, there is destruction of hair follicle in association with mixed inflammatory infiltrate.
Fungal forms may be difficult to appreciate on H&E. (Right) PAS-D highlights fungal hyphae within the hair follicle in this example of
Majocchi granuloma.
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