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Journal of Clinical Microbiology, March 2000, p. 1283-1285, Vol. 38, No. 3
0095-1137/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Report of the First Human Case of Lobomycosis
in the United States
Robert A.
Burns,1
J. Stephen
Roy,2
Cavan
Woods,1
Arvind A.
Padhye,3,* and
David W.
Warnock3
North Georgia Surgical Associates, Dalton,
Georgia 307221; Dianon Systems Inc.,
Stratford, Connecticut 066152; and
Mycotic Diseases Branch, Division of Bacterial and Mycotic
Diseases, National Center for Infectious Diseases, Centers for
Disease Control and Prevention, Atlanta, Georgia
303333
Received 30 August 1999/Returned for modification 27 October
1999/Accepted 27 December 1999
 |
ABSTRACT |
We describe the first human case of lobomycosis caused by
Lacazia loboi in a 42-year-old white male resident of
Georgia. The patient had traveled to Venezuela 7 years earlier, where
he had planned to rappel down Angel Falls in Canaima. Although he never actually rappelled the falls, he did walk under the falls at least three times, exposing himself to the high water pressures of the falls.
He noticed a small pustule with surrounding erythema developing on the
skin of his right chest wall. The lesion gradually increased in size
and had an appearance of a keloid. For cosmetic reasons, the patient
sought medical treatment to remove the lesion. After an uncomplicated
excision of the lesion, the patient recovered completely. The excised
tissue was fixed in formalin for pathologic examination. Tissue
sections stained by hematoxylin and eosin, periodic acid-Schiff stain,
and Gomori methenamine silver stain procedures showed numerous
histiocytes, multinucleated giant cells, and numerous globose or
subglobose, lemon-shaped cells producing multiple blastoconidia
connected by narrow tube-like connectors and catenate chains of various
lengths characteristic of L. loboi.
| |
TEXT |
Lobomycosis is characterized by
slowly developing variably sized cutaneous nodules after a traumatic
event. The dermal nodules manifest as either smooth, verrucose, or
ulcerated surfaces which can attain the size of a small
cauliflower-like keloid (7, 11). The onset of the disease is
generally insidious. The increase in size or number of lesions is a
slow process, progressing over a period of 40 to 50 years
(11). The lesions are composed of granulomatous inflammatory
tissue containing numerous globose or subglobose to lemon-shaped,
yeast-like fungal cells singly or in simple and branched chains.
The etiologic agent of lobomycosis is an obligate pathogen of humans
and lower mammals which has yet to be isolated and grown in vitro;
therefore, nothing is known of its basic cultural characteristics and
growth (3). Diagnosis is based on demonstrating the presence of globose, thick-walled yeast-like cells ranging from 5 to 12 µm in
diameter in lesion exudate or tissue sections. The organism multiplies
by budding, and thus mother cells with single buds are often observed.
However, characteristic sequential budding leads to the production of
chains of cells that are linked to each other by a tubular connection,
or isthmus. Budding may occur at more than one point on a cell, giving
rise to branched or radiating chains of cells. These thick-walled,
hyaline, spherical cells with chains of cells interconnected by tubular
connections are the basis on which a diagnosis of lobomycosis rests.
The thick-walled, budding hyaline cells with catenate chains of conidia
can be readily observed in tissue smears or exudates mounted in 10%
KOH or in Calcofluor mounts (3). Surgical excision of
localized lesions or single plaque infections is the optimal therapy.
In cases involving larger areas of infection, treatment with
clofazimine (Lamprene) is recommended. At present, the disease does not
have a satisfactory medical treatment (11).
A new monotypic genus, Lacazia, with Lacazia
loboi as the type species, was recently proposed by Taborda et al.
(15) to accommodate the obligate etiologic agent of
lobomycosis in mammals. The continued placement of L. loboi
in the genus Paracoccidioides as Paracoccidioides
loboi O.M. Fonseca et Lacaz was found to be taxonomically
inappropriate. The older name Loboa loboi Ciferri et al. was
considered to be a synonym of Paracoccidioides brasiliensis (15).
The human disease is endemic in the tropical zone of the New World and
has been reported in central and western Brazil, Bolivia, Colombia,
Costa Rica, Ecuador, Guyana, French Guiana, Mexico, Panama, Peru,
Suriname, and Venezuela (11). There have been isolated cases
reported in Holland (5, 14) and a doubtful case in
Bangladesh (12, 15). Identification of the disease in
dolphins widened the geographic distribution of the disease. Seven
cases of lobomycosis involving two species of dolphins, namely, marine
dolphins (Tursiops truncatus) and marine freshwater dolphins
(Sotalia fluviatilis) (4, 15), have been reported for Florida, the Texas coast (2, 4, 8), the Spanish-French coast, the South Brazilian coast, and the Suriname River estuary (11, 15). Even though lobomycosis in dolphins has been
reported in the United States, to our knowledge no human infection has been reported so far. We describe the first human case of lobomycosis in the United States in a white male resident of Georgia. The patient
gave a history of travel to Venezuela, one of the countries where
lobomycosis is endemic.
Case report.
A 42-year-old white male patient, a resident of
Georgia, presented to a general surgeon. The patient requested removal
of a skin lesion on his right chest wall for cosmetic reasons. Seven years earlier, the lesion had started as a small pustule with surrounding erythema. At that time, the patient pierced the pustule with a needle and then expressed a tiny amount of bloody fluid. Afterwards, the lesion developed into a small nodule that gradually increased in size. Some mild itching was associated with the lesion but
there was no pain or discomfort.
Two and one-half years prior to the appearance of the pustule, the
patient had traveled to Venezuela, where he had planned to rappel down
Angel Falls in Canaima. Although he never actually rappelled the falls,
he did walk under the falls at least three times. On each of these
occasions, he was exposed to extremely high water pressures due to the
height (3,000 ft) of the falls. Each exposure lasted around 30 min.
Although he was wearing a diving suit, he said that the water
penetrated the suit, leaving him soaked. He also swam in the river at
the bottom of the falls. His only previous travel outside the United
States involved two trips to Mexico in the late 1980s, during which he
performed vertical rappelling in caves. His only water exposure during
the Mexican trips was limited to showering in the local facilities. He
was not aware of any injury to the skin during any of these adventures.
On physical examination, the patient was found to have a raised 3.5- by
2-cm reddish purple nodule with a smooth surface and
distinct margins
located on the right chest wall in the midaxillary
line at the level of
the eighth rib. It had the appearance of
a keloid. After an
uncomplicated excision, the excised tissue
was sent for pathologic
evaluation.
Histologic examination.
The excised tissue, fixed in formalin,
was a skin ellipse which measured 4.9 by 2.6 by 0.6 cm, with the lesion
measuring 3.5 by 2.1 cm. No fresh tissue was saved for bacterial or
fungal cultures. Tissue sections were prepared and stained by
hematoxylin and eosin, periodic acid-Schiff stain, and Gomori
methenamine silver stain procedures. Microscopic examination of the
tissue sections showed a nodular inflammatory infiltrate of foamy
histiocytes, multinucleated giant cells, and scattered lymphocytes.
Throughout the infiltrate were numerous globose or subglobose,
lemon-shaped cells that measured 5.0 to 11.0 µm in diameter. Many
cells showed thick refractile walls and reproduced by single and
multiple budding. The buds were attached to the mother cell by narrow
tubular connections, giving a beaded appearance. There were many chains
of cells showing narrow tubular connections (Fig.
1 and 2)
characteristic of L. loboi (3, 7, 15).
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FIG. 1.
Excised tissue section showing globose and subglobose
budding cells and chains of blastoconidia of L. boboi.
Gomori's methenamine silver stain was used. Magnification, ×140.
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FIG. 2.
Globose to subglobose cells in a chain with distinctive
tubular connectors and a cell showing multiple buds. Gomori's
methenamine silver stain was used. Magnification, ×770.
|
|
The globose and subglobose budding cells of
L. loboi
resemble budding cells of
P. brasiliensis in tissue.
However, the central
mother cells of
P. brasiliensis become
large and thick-walled
compared to the daughter cells, which remain
smaller. In contrast,
yeast cells of
L. loboi remain
consistent in diameter, giving
rise to branching chains of
blastoconidia (
15). In addition,
according to Taborda et al.
(
15), the cell wall of
L. loboi contains
constitutive melanin, which can be detected by the use
of the
Fontana-Masson histologic stain. The walls of cells of
P. brasiliensis are not known to contain melanin.
L. loboi
has
never been cultured in vitro. On the other hand,
P. brasiliensis can be grown in artificial culture and is known to be
a dimorphic
pathogen.
With the greater frequency of international travel, many cases of
endemic mycosis are often diagnosed in areas of nonendemicity.
In
the United States, cases of paracoccidioidomycosis (a disease
endemic
in Latin America), African histoplasmosis (endemic in
Africa), and
penicilliosis marneffei (endemic in Southeast and
Far East Asia) have
been diagnosed (
1,
6,
9,
10,
13)
in patients with a history
of travel or residence in the areas
of endemicity. The case histories
of such imported mycoses often
illustrate an important feature of these
diseases, namely, their
long dormancy periods. These diseases often go
through a remarkably
long quiescent period of no symptoms. These
dormancy periods may
range from a few months to several years
(
1). In lobomycosis,
the onset of the disease is generally
insidious and difficult
to document. The increase in size and number of
lesions is a slow
process; it can take 40 to 50 years (
11).
This latency period
often makes it important to note the patient's
history of travel
or stay in areas of endemicity to arrive at a proper
diagnosis.
In the present case, the incubation period was 7 years. The
history
often reveals the cause being a trauma, for example, an
arthropod
sting, a snake bite, a cut from an instrument, or a wound
acquired
while cutting vegetation. The causal agent of lobomycosis
appears
to be saprobic in aquatic environments, which probably plays an
extremely significant part in its life cycle (
11). In the
present
case, the patient's listed activity involved exposure to high
water pressures due to the height of the water falls and swimming
in
the river. The surgical excision led to uncomplicated cure
of the
infection.
| |
FOOTNOTES |
*
Corresponding author. Mailing address: Mycotic Diseases
Branch, Mail Stop G-11, Centers for Disease Control and Prevention, Atlanta, GA 30333. Phone: (404) 639-3749. Fax: (404) 639-3546. E-mail:
aap1{at}cdc.gov.
| |
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Journal of Clinical Microbiology, March 2000, p. 1283-1285, Vol. 38, No. 3
0095-1137/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
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