2023, Volume 39, Number 3, Page(s) 206-211
Lobomycosis in a Post-Covid 19 Patient: A Case Report and Review of Literature
Sateesh S CHAVAN1, Thotadamane Nagaraja CHANDRASHEKHAR2
1Departments of Pathology, Karnataka Institute of Medical Sciences, KARNATAKA, INDIA
2Shivamogga Institute of Medical Sciences, KARNATAKA, INDIA
Keywords: Lobomycosis, Lacaziosis, Chain of yeasts, Sequential budding, Connecting tubes
To document a case of lobomycosis and to discuss its epidemiology & diagnosis.
Case Report: A 53-year-old male presented with a history of nasal congestion, nasal discharge, and epistaxis following Covid 19 infection. On
physical examination, there was necrotic slough in the nasal vestibule near the inferior turbinate. Scrapings and punch biopsy were taken from
the lesion. Hematoxylin-eosin-stained sections showed necrotic and mucoid areas with mixed inflammatory cell infiltration and numerous
budding yeasts 3- 7μm diameter in singles, and small clusters with single narrow based budding as well as multiple budding including sequential
budding forming “chains of yeasts”. A diagnosis of Lobomycosis was made. Yeasts of lobomycosis are often confused with other yeasts such
as P. brasiliensis, Candida spp., B. dermatitidis, and Cryptococci, but characteristic ‘sequential budding’ with a ‘chain of yeasts” aid in the final
diagnosis. Demonstration of yeasts with characteristic chains either in tissue sections or in potassium hydroxide (KOH) preparation of scraped
material, exudate, or exfoliative cytology is the mainstay in the diagnosis as the organisms are uncultivable in vitro in culture medium.
Lobomycosis is a chronic fungal infection caused by Lacazia
loboi, a disease of humans and dolphins that is highly
prevalent in tropical and coastal regions of Central and
South America. The disease is often seen among forest
workers, veterinarians, marine biologists, and those handling
aquariums and is usually contracted following traumatic
inoculation of organisms into subcutaneous tissue.
Epidemiologically, the disease can be considered an occupational
hazard as well as zoonotic. The most common
presentation is ‘keloid like’ subcutaneous nodules (hence
the name ‘keloidal blastomycosis’) on extremities and
other exposed areas. The disease is diagnosed by demonstration
of sequentially ‘budding yeasts’ forming a ‘chain
of yeasts’ either in tissue sections or potassium hydroxide
(KOH) preparation of exudate or exfoliative cytology of
scrapings from lesions. The organism has not been isolated
and grown in vitro in culture medium so far 1-3
Here, we present a case of lobomycosis in a post-Covid 19
A 53-year-old male carpenter by occupation presented with
history of nasal congestion and nasal discharge, often with epistaxis. There was a history of recovery from Covid-19
infection. During his stay in quarantine with hospitalization,
he had recurrent fever with maintained O2 saturation
(ranged from 92% to 98%) and normal lung fields on high
resolution computed tomography. He was on medication
such as Azithromycin, Dexamethasone, Tamiflu, Ivermectin,
Paracetamol, Zinc, and vitamin C. During the quarantine
period, his laboratory investigations showed raised
levels of C-reactive protein, D-dimer, random blood sugar
(12.88mmol/L), ferritin levels, and lactate dehydrogenase
levels.. He was a known diabetic and hypertensive, and
was on short-term insulin therapy during the quarantine
period. There was no travel history to tropical regions. He
developed nasal congestion with discharge 4 weeks after
recovery from the Covid-19 infection. Physical examination
revealed a crusted ulcerative lesion with necrotic
slough in the left nasal vestibule near the inferior turbinate.
His routine investigations showed hemoglobin of 131gm/L,
total leukocyte count of 9.3 x 109
cells/L with neutrophilia,
platelet count of 210 x 109
cells/L, RBS-9.325mmol/L, ESR-
40mm/1st hour, blood urea 1.887mmol/L and serum creatinine
He underwent curettage and material was sent for fungal
culture and histopathological examination. Fungal culture
did not yield any growth.
Formalin fixed paraffin embedded hematoxylin & eosinstained
sections showed necrotic and mucoid areas with
mixed inflammatory cell infiltration including neutrophils,
lymphocytes, and histiocytes (Figure 1). Amidst these are
seen variably sized yeasts measuring 3- 7μm diameter with
well delineated thick hyaline refractile wall, dispersed singly,
in small clusters as well as in radiating chains. They showed ‘single’ narrow based budding (Figure 1,2) as well
as ‘multiple’ narrow based budding including ‘sequential
budding’ resulting in “chains of yeasts” (Figure 3A,C,D, and
Figure 4A-D,F,G) and multiple ‘non sequential budding
(Figure 3G and Figure 4E,I,L). Characteristically, the parent
cell and daughter cells were connected by ‘narrow stalk’ or
“tube like isthmus” (also called ‘connecting tubes’) (Figure 3E,F and Figure 4E). Also, detached cells showed ‘retained
tube like structures’ on one cell (Figure 3C and Figure
4J,M) and ‘bud scars’ on the other (Figure 4K). ‘Tube like
structures’ were also observed in yeasts with multiple ‘non
sequential budding’ (Figure 4E,I,L). Occasionally, budding
yeasts showed “hour glass appearance” due to elongation of
connecting tubes (Figure 4H). The organisms were GMS
(Gomori’s methenamine silver nitrate stain) positive (Figure
2,4). Histopathological diagnosis of lobomycosis was
The patient was given intravenous injection of broad-spectrum
antifungal agent ‘liposomal Amphotericin B’ (1mg/
kg) for the first 5 days and continued on days 14 and 21.
In addition he was administered a combination of Itraconazole
(100mg/day) and Clofazimine (100mg) daily for
6 months. After 9 months of follow up, the patient was free
from recurrence. The patient was out of further follow-up.
Click Here to Zoom
|Figure 1: Numerous budding yeasts in mucoid & necrotic
background [Haematoxylin & Eosin x 100].
Click Here to Zoom
|Figure 2: Numerous budding yeasts in mucoid & necrotic
background [Gomori’s methenamine silver nitrate stain x 100].
Click Here to Zoom
|Figure 3: H & E. [Fig A, x 40; Fig B, C, D, x 100; Fig E, F, G x 200]. Numerous thick walled ‘narrow based’ budding yeasts in a mucoid
to necrotic background, many of which show ‘tube like isthmus’ connecting parent cell with daughter cells [3E, short black arrow head].
Many of these yeasts show ‘retained tube’ after the detachment from parent cell [3B&C, short black arrow head]. They also showed
characteristic multiple ‘sequential’ budding resulting in ‘chain of yeasts’ [3A, C, D &E, long black arrow heads] and multiple irregular ‘non
sequential’ budding [3G, short black arrow head].
Click Here to Zoom
|Figure 4: Gomori’s methenamine silver nitrate stain. [Fig A, B, C, E, F, G, I, J, L x 100; Fig D, H, K, M x 200]. Yeasts showed characteristic
multiple ‘sequential’ budding resulting in ‘chain of yeasts’ [4A, B, C, D, F & G, long black arrow heads] and multiple irregular ‘non
sequential’ budding [4E, I & L, short black arrow head]. Many of which show ‘tube-like isthmus’ connecting parent cell with daughter
cells [4E, short black arrow head] and ‘retained tube’ after the detachment from parent cell [4J&M, short black arrow head]. They also
showed characteristic ‘bud scars’ [4K, long black arrow heads]
Lobomycosis, an emerging and enigmatic tropical disease,
is a self-limited chronic subcutaneous mycosis also called
‘Jorge Lobo Blastomycosis,’ keloidal blastomycosis, pseudo
lepromatous blastomycosis, Caiabi leprosy, and Lacaziosis.
It was first described by the dermatologist Jorge Lobo in
1931 in a middle-aged forest worker 1,2
. It is a disease
of dolphins & humans, and to date, around 500 cases have
been reported so far. Most cases occurred in the regions of
the Amazon basin of South America and Central America
in which climatic characteristics of tropical regions are
suitable for organisms, making it the region the with highest
number documented cases. The rest occurred in coastal
regions of the United States, Europe, and South Africa and
very few cases are reported in Asia including India 1,2
The disease can be considered an occupational hazard (forest
workers, veterinarians, marine biologists) or it can be
zoonotic particularly amongst aquarium workers who deal
with rescue operations of dolphins 1-17
It is caused by the fungi ‘Lacazia loboi.’ The fungus belongs
to the order Onyganeles, family Ajellomycetes, genus Paracoccidioides,
and species Lacazia loboi. The fungus has
not yet been cultured and isolated so far. Because of the
difficulty in culture and isolation of the agent, taxonomic
nomenclature was difficult and challenging, and hence it
was variably called Glenosporella loboi, Blastomyces brasiliensis,
Glenosporosis amazonica, Paracoccidioides loboi,
Blastomyces loboi, and Lobomyces loboi. However, these
terms were considered invalid and ‘Lacazia loboi’ has been
proposed and followed 4,7,9,10.
Though some characteristics of Paracoccidioides brasiliensis
and Lacazia loboi’ put them in the same taxonomic
complex, they are phylogenetically distinct 3. Despite
many attempts to isolate the organism by inoculations of
animals including mice, armadillo, and turtles, they were
unsuccessful 1,2,3,10. The fungus is saprophytic and
probably hydrophilic. Although soil and vegetation appear
to be the natural habitat, many cases are reported in marine
and aquatic environment indicating that L. loboi may be a
hydrophilic microorganism 3-5.
The lesions of lobomycosis are usually limited to the epidermis
and dermis and rarely involve subcutaneous tissue.
They are pleomorphic ranging from macule, papule, ulcerative,
nodular sclerodermiform, and verrucoid. Most cases
present with freely mobile subcutaneous, painless, pruritic
nodules over exposed areas like the face, ears and extremities.
They grow over a period of weeks or months to form
large verrucoid or ulcerative nodules, often with satellite
Often there is traumatic inoculation of the organism into
the subepithelial zone where dermal macrophages phagocytose
them followed by proliferation of yeasts. These
phagocytes and activated Th2 lymphocytes secrete antiinflammatory
cytokines including transforming growth
factor β1(TGF β1) and IL-10. TGFβ1 inhibits the phagocytic
activity of macrophages, and inhibits Nitric oxide and
IFN-ϒ expression, creating a localized immunodeficient
state and finally stimulates the process of fibrosis. Once in
the subepithelial zone, the yeasts can access the lymphatics
and can disseminate to other sites. The ‘satellite lesions’
observed in lobomycosis are often due to autoinoculation,
and less commonly due to lymphatic spread. Clinically and
pathophysiologically, the disease resembles lepromatous
leprosy and cutaneous leishmaniasis, all of them presenting
as an antigen specific immunodeficient state 4,12.
In the present case, the patient presented with a friable to
firm crusted and ulcerated lesion covered with slough over the left nasal vestibule associated with nasal congestion
and mucoid discharge from the maxillary sinus. Though
in most cases there is no predisposing factor, in conditions
of altered immunity the fungi proliferate and lesions tend
to progress and may disseminate 1-5. In the present case,
the patient was a known diabetic and recently recovered
from Covid 19 infection, which might have contributed to
Since the organism is uncultivable, the diagnosis of lobomycosis
is based on demonstrating the thick-walled hyaline
spherical yeasts either in exudates using KOH (potassium
hydroxide) preparation or in exfoliative cytology of the
ulcerative lesion or in tissue sections with hematoxylin &
eosin stain. However, histopathology is the ‘gold standard’
for establishing the diagnosis. Special staining techniques
such as Gomori’s methenamine silver nitrate stain, Periodic
acid Schiff stain, or Calcofluor stain can be used to
readily demonstrate yeasts 1,2,4,5,18,19.
In Hematoxylin & Eosin stained tissue sections, the yeasts
are faintly stained, and are ‘doubly refractile’, birefringent
thick-walled hyaline round to oval ‘lemon shaped,’ 3-
7μm in diameter, with amphophilic to slightly basophilic
homogeneous cytoplasm. The yeasts usually reproduce by
single narrow based budding with ‘tube-like structures’
or ‘isthmus’ connecting one another and typically they
show formation of ‘chains of 2- 5 yeasts’ due to ‘sequential
secondary budding’ from daughter cells. When budding
is ‘multiple’ occurring on different points on the same
cell with subsequent ‘secondary sequential budding’ from
daughter cells, this results in the formation of ‘radiating
chains of yeasts’ 2. Characteristically one of the budded
cells (usually daughter cells) show ‘bud scars’ and the other
(usually parent cell) show ‘retained tube-like structure.’
Some yeasts also exhibit elongation of ‘connecting tubes’
resulting in ‘hour glass’ appearance (hour glass yeasts).
Although pseudo-hyphae formation is rare, this elongation
of connecting tubes may represent pseudo hyphae formation
1,2,4,5,18,19. In the present case, the organisms
with their characteristic morphology including ‘chains of
yeasts,’ bud scars, and tube-like structures were easily recognized
in GMS stain.
The tissue response is variable from case to case, ranging
from granulomatous inflammation in the dermis with
hyperplasia of the overlying epidermis to suppuration with
necrosis. Though the tissue response is variable from case
to case, tinctorial morphology of the fungi are remarkably
similar in all cases. Yeasts, once they enter the tissue, elicit
either an ‘antigen specific granulomatous response’ rich in
granulomas, multinucleated giant cells and with absent to minimal necrosis (most common) or create an ‘antigen specific
immunodeficient state’ with necrosis and suppuration
rich in neutrophils, lymphocytes, histiocytes and minimal
to absent granulomas (less common). Typically, the dermis
shows granulomas comprising epithelioid histiocytes and
multinucleated giant cells including Langhans giant cells.
The stromal fibrosis is also variable, usually minimal, and
shows a narrow delicate network of reticulin fibers that
surround and may extend into granulomas. They are well
demonstrated by Masson-Trichrome stain. It is unusual to
see suppuration and necrosis in lobomycotic lesions. The
present case showed abundant degenerated mucoid and
fibrinoid necrotic material with mixed inflammatory cells
including neutrophils and histiocytes. Fibrosis and welldefined
epithelioid cell granulomas were absent.
Lobomycosis is confused with other yeasts or yeast like
organisms that show budding such as P. brasiliensis, Candida,
Cryptococci, and B. dermatitidis. Paracoccidioides
brasiliensis, which also reproduce by single and multiple
budding, may be confused with lobomycosis. However,
P. brasiliensis do not form ‘chains of cells ‘with ‘connecting
tubes’ (which are typical of lobomycosis). The daughter
cells of P. brasiliensis are usually smaller in size than
the parent cell, whereas the daughter cells of lobomycosis
usually are larger or are of the same size as the parent cell
1,2,4,5. Budding yeasts of Candida may also be confused
with that of Lobomycosis but absence of pseudohyphae
and presence of typical ‘chain of yeasts’ and ‘tube like isthmus’
will aid in diagnosis of the latter. Occasionally, some
Cryptococci show multiple budding. The typical ‘chain
of yeasts’ is absent. One can see with careful search the
typical’ mucoid’ capsule (that is absent in lobomycosis).
Infrequently, Blastomyces dermatitidis also show multiple
budding but typically they are ‘broad-based’ and they do
not form a ‘chain of yeasts.’ The cell walls of B. dermatitidis
are thick and doubly refractile 1,2,4,5. Further P. brasiliensis,
Candida, Cryptococci, and B. dermatitidis can be
grown in vitro in culture and isolated but not lobomycosis.
The mainstay of treatment is surgical excision or curettage
or cryosurgery for recurrent cases. None of the antifungals
proved effective. Itraconazole has shown partial response;
hence it is often used with cryosurgery for recurrent cases.
The newer azoles such as Posaconazole used along with
wide local excision have proven effective with no remission
1,2,4,5. The present case was treated with combined Itraconazole
and Clofazimine along with intravenous Amphotericin
B, and showed no recurrence in the follow up
period of 9 months. It is also observed that some cases with
concurrent leprosy (particularly in endemic areas such as Amazon basin regions) responded well to multi drug therapy
with Clofazimine and Rifampicin in combination with
newer azoles 4. In the present case, the patient was also on
Clofazimine in addition to Itraconazole and Amphotericin
B, and responded well with no recurrence in the short term
follow up period.
In conclusion, Lobomycosis is highly prevalent in tropical
regions and coastal regions of Central and South America,
but can be seen sporadically all over the world where
there is tropical climate. Histopathology is the mainstay in
diagnosis as the organism is uncultivable in vitro in culture
medium. Demonstration of budding yeasts with characteristic
‘sequential budding’ resulting in ‘chains of yeasts’ is an
important finding which aids in the diagnosis. Identification
of the organism is important as none of the antifungal
drugs are effective and the mainstay in treatment is wide
surgical excision combined with newer azoles.
Conflict of Interest
The authors declare that there is no conflict of interest.
Concept: SSC, Design: SSC, Data collection or processing: SSC,
TNC, Analysis or Interpretation: SSC, Literature search: SSC, TNC,
Writing: SSC, Approval: SSC, TNC.
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