Mycology- Chromoblastomycosis

1. Name: Purshotam Kumar Sah Kanu
Roll No.: MB 1318/075
Level: M.Sc Microbiology (3rd Sem)
Central Department of Microbiology
Tribhuvan University, Kirtipur
Kathmandu, Nepal
MB 609 Systemic and Diagnostic
Mycology

2. Introduction
 Chromoblastomycosis is a chronic fungal infection
acquired through traumatic inoculation of an organism,
primarily into the skin and subcutaneous tissue.
 The infection is characterized by the development of a papule
at the site of the traumatic insult that slowly enlarges to form
warty or tumorlike lesions characterized as resembling
cauliflower capable of spreading through the lymphatic system.
 Secondary infection and ulceration may occur.
 The lesionsusually are confined to the feet and legs but may
involve the head, face, neck, and other body surfaces.

3.  The term chromomycosis includes chromoblastomycosis and
phaeohyphomycosis caused by dematiaceous fungi.

4. Chromoblastomycosis
• This disease, also known as chromomycosis,is a chronic,
localized disease of the skin and subcutaneous tissues,
characterized by crusted, warty lesions usually involving the
limbs.
• The disease is mainly encountered in the tropics.
• Like mycetoma, the disease is seen most often among males
in rural areas.
 Chromoblastomycosis is a slowly progressing granulomatous
 infection caused by several soil fungi.
 These are Fonsecaea pedrosoi, Fonsecaea compactum, Cladosporium
carrionii, and Phialophora verrucosa.

5. Cont..
 These fungi are collectively called dematiaceous fungi
because they have brown to black melanin pigment in their
cell wall, and their conidia or hyphae are dark colored, either
gray or black.
 All the fungi causing chromoblastomycosis appear
morphologically similar in tissues stained by hematoxylin
and eosin (H and E) or other stains.
 The infection occurs following introduction of any of the
dematiaceous fungi into the skin through trauma.
 The development of warty nodules that appear at site of
inoculation characterizes chromoblastomycosis.

6. Cont..
 During the course of infection, these lesions vegetate and
develop to a cauliflowerlike lesion.
 The disease is more common in tropical and subtropical
countries.

7. Etiological Agents
 The etiological agents are soil inhabiting fungi of the
family Dematiaceae.
 All are dematiaceous fungi, having melaninized cell walls.
 These include: Phialophora verrucosa,Fonsecaea pedrosoi,
Rhinocladiella aquaspersa,Fonsecaea compacta and
Cladophialophora carrionii.
 They enter the skin by traumatic implantation.
 The lesion develops slowly around the site of implantation.
 The infection is chronic and characterized by the slow
development of progressive granulomatous lesions that in
time induce hyperplasia of the epidermal tissue.

8. Table: Important causative agents and colour of the grains
of various types of mycetoma
Causative agent Color of the grains
A. Eumycetoma
• Madurella mycetomatis Black
• M.grisea Black
• Exophiala jeanselmei Black
• Curvularia geniculata Black
• Pseudallescheria boydii White-yellow
• Acremonium kifiense White-yellow
• Aspergillus nidulans White
• Fusarium species White
B.Actinomycetoma
• Actinomadura madurae White-yellow
•A. pellitieri RedYellow

9. Causative agent Color of the grains
• Nocardia asteroids White-yellow
• N.brasiliensis White
• Nocardiopsis dassonvillei Cream
• Streptomyces somaliensis Yellow
C. Botryomycosis
• Staphylococcus species White
• Streptococcus species White
• Escherichia coli White
• Proteus species White
• Pseudomonas aeruginosa. White
• Actinobacillus lignieresi Yellow

10. Epidemiology
 Chromoblastomycosis is reported worldwide mainly in
tropical and subtropical regions includingWest Indies,
Brazil, NewVenezuela, Madagascar, China, Japan,Philippines,
Malaysia, and India.
 Sub-Himalayan, eastern and western coastal areas in India
have endured the most of the disease.
 In Mexico, chromoblastomycosis is mostly found in the
southeastern states having tropical/subtropical climatic
conditions.
 Chromomycosis occurs secularly in all races including
European,Asian, LatinAmerican, andAfrican population.
 They are 10 times more likely to possess human leukocyte
antigen serotype (HLA-A29) histocompatibility antigen.

11. Pathogenesis
 F.pedrosoi is the commonest pathogen (90% of cases) in
humid and tropical regions.
 The Rhytidhysteron species has been implicated in causing
chromoblastomycosis in a renal transplant patient.
 Although most individuals have no underlying disease or
debility, the infection has been noted in conjunction with
malignancy,leprosy, immunosuppression, organ transplant or
corticosteroids use.

12. Clinical Features
 The initial lesion is a small, painless, papule at the site of inoculation.
 The exposed body parts are commonly involved.
 After a long incubation period; this enlarges to form warty nodules or
plaques (Fig. 7).
 Multiple, nodular, tumoral, hyperkeratotic verrucous plaques,
usually unilateral and seldom associated with pruritus or pain, are
common (Fig. 8).
 Autoinoculation or superficial lymphatic spread can lead to satellite
lesions.
 Rare extracutaneous spread to lymph nodes, brain, ileocecal region,
tonsils, tracheobronchial tree, lungs, pleural cavity, and bone has been
reported.
 Development of squamous cell carcinoma in a chronic lesion is well-
known.

13. Figs 7A and B: Chromoblastomycosis:Verrucous plaques over
heel. Lesions of long-standing duration result in large,
verrucous or cauliflower-like plaque formation

14.  Figs 8A and B: Chromoblastomycosis. (A) Large, hyperkeratotic,
 superficial, scaly, verrucous plaque over elbow, and (B) Over
 dorsal hand. Small, dark aggregations of clotted blood and fungal
 cells are characteristic and likely to yield fungal cells in smears or
 histologic sections
Figs 8A and B: Chromoblastomycosis. (A)
Large, hyperkeratotic, superficial, scaly,
verrucous plaque over elbow, and (B)
Over dorsal hand. Small, dark
aggregations of clotted blood and fungal
cells are characteristic and likely to
yield fungal cells in smears or histologic
sections
Fig. 9: Chromoblastomycosis.
Sclerotic bodies, as seen in
potassium hydroxide mounts, are
5–13 μm, round, thick-walled,
brown muriform cells, having
longitudinal and transverse septa

15. Box 1: Differential diagnoses for
chromoblastomycosis
 Tuberculosis verrucosa cutis
 Fixed cutaneous sporotrichosis
 Foreign body granuloma
 Lupus vulgaris
 Leprosy
 Cutaneous leishmaniasis
 Common warts
 Malignancy including squamous cell carcinoma and
keratoacanthoma

16. Laboratory Diagnosis
A. Microscopic Examination:
 The dark-colored fungal elements are relatively easy to see on
microscopical examination of skin scrapings, crusts and pus.
 The agents of chromoblastomycosis are identified by their modes
of conidiation.
 Histologically, the lesions show the presence of the fungus as
round or irregular, dark brown, yeastlike bodies with septae,
called sclerotic cells (Fig 73.7).
 Diagnosis can be established by demonstration of these sclerotic
bodies in KOH mounts or in sections and by culture on
Sabouraud’s agar.

17. Cont..
Fig. 73.7: Chromblastomycosis: KOH mount of lesion large septate
„scierotic bodies‟

18. • Figure 60-1 Sclerotic bodies from the tissue of a patient
with chromoblastomycosis (3400). (FromVelasques LF,
Restrepo A: Chromomycosis in the toad (Bufo marinus)
and a comparison of the etiologic agent with fungi
causing human chromomycosis, Sabouraudia 13:1,1975.)

19. B. Histopathology
 Histological features include pseudoepitheliomatous
epidermal hyperplasia, granulomatous inflammation with
foreign body giant cells, and areas of microabscess formation.
 Fibrosis occurs in longstanding cases.
 The muriform cells (sclerotic or copper penny bodies) are
often seen in the deeper sections, whereas hypha and
budding cells are present near the lesion surface.
 Nevertheless, the presence of fungal cells or the copper
penny bodies, singly or in clusters, found within giant
cells is pathognomic (Fig. 10).

20. A B
Figs 10A and B: Chromoblastomycosis: Histopathology -
pseudoepitheliomatous hyperplasia, granulomatous
inflammation with foreign body giant cells, and areas of
microabscess formation. Demonstartion (arrows) of “sclerotic
or copper penny bodies” (A) especially within the giant cells
(B) is pathognomic (H & E × 40)

21. C. Culture:
 Culture from skin scraping/biopsy tissue of the causative
fungus in SDA is attempted.
 Culture is important for species differentiation.
 Lesional biopsy material, crusts or pus is incubated at room
temperature for at least 4-6 weeks.
 Colonies on SDA, vary greatly in morphology though they
are deeply pigmented, gray, dark olive gray, dark brown or
nearly black (Fig. 11).
 The causative fungus can be identified by colony
morphology, characteristic sporulation, arrangement of
conidia and morphology of the conidiogenous cell (Fig. 12).

22. Fig. 12. Chromoblastomycosis: Fonsecaea
pedrosoi, seen as broad, septate hyphae.
Conidia are one celled and broadly
clavate with flat base and arise from the
swollen apex of the conidiophore. Each
conidium form several conidia in
repeating process and form complexly
branched head termed as “Fonsecaea
synanamorph” that is considered as
most distinct (arrow). (Lactophenol
cotton blue × 40)
Fig. 11: Chromoblastomycosis:
Colonies of Fonsecaea pedrosoi, the
commonest pathogen, in
Sabouraud‟s glucose agar are
olivaceous-black and velvety in
texture. However, clinically the
lesions of chromoblastomycosis
appear morphologically similar
regardless of the implicated
organism

23. D.Serodiagnosis/Molecular Diagnosis
 Serological tests are not used routinely.
 The available methods are based on identification or
amplification of specific deoxyribonucleic acid (DNA)
from ribosomal or internal transcribed spacer (ITS)-1and
ITS-2 regions of the ribosomal deoxyribonucleic acid (rDNA)
and the 5.8S sequence.
 There are no diagnostic serological tests available
commercially.

24. Treatment
 The drug of choice for treatment of chromoblastomycosis is
5-fluorocytosine.
 Cautery and surgical removal of early lesion is also useful.

25. Treatment
 Spontaneous resolution is very rare and treatment is difficult as
response to drugs is limited. Infections caused by F.pedrosoi tend
to be more resistant. Untreated, the risk of complications like
recurrent secondary infections, distant/extracutaneous spread,
malignant change, and risk of chronicity needs to be kept in
mind.
 Small lesions of shorter duration are at best amenable to local
destruction by surgical excision, cryotherapy, CO2 laser or
local heat therapy.Treatment with SSKI alone or in combination
with other antifungal agents is widely used for more extensive
lesions.

26. Cont…
 Currently, itraconazole, and terbinafine are recommended drugs.
 Itraconazole (200–400 mg/day) or terbinafine (500 mg/day) is
given over a period of 6–18 months or longer.
 Itraconazole monotherapy for 18–30 months has shown good
response even in pulse schedules.
 Addition of 5-flucytosine (5-fluorocytosine) (50–150 mg/kg/day
divided in four equal doses) may also improve therapeutic
outcome.
 Amphotericin B is administered intravenously (0.5–1.0
mg/kg/day not exceeding 1.5 mg/kg/day).
 It is rarely effective when given alone and is best used in
combination with intralesional injections.

27. Cont….
 Poirriez et al. observed using two or more treatment
modalities, yield better results.
 Sequentially, combination of intravenous amphotericin B and
oral 5-flucytosine (4 g/day) for first 1 month, followed by
oral itraconazole (200 mg/day) and 5-flucytosine for next 12
months yielded successful cure.
 As there are no well-defined clinical or experimental criteria
for stopping systemic antifungal treatment or achieving cure,
recurrences may occur after partial treatment.

28. Cont….
 Ketoconazole has not been found effective and results have
been variable with thiabendazole.
 Voriconazole and posaconazole have shown a broad spectrum
in vitro and in vivo antifungal activity against dematiaceous
fungi.
 Posaconazole (400 mg twice daily), in combination with
topical heat therapy or surgical excision has demonstrated
efficacy.
 Voriconazole alone, 200 mg twice daily for 12 months,
showed only partial response.

29. Cont….
 Topical heat therapy using chemical or electric pocket
warmers at 42–46°C is another effective option.
 It is safe, does not cause discomfort and results are seen in
relatively short time of 2–6 months, combined with CO2
laser, it produces better results.