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Bangladesh Journal of Medical Science Vol. 13 No. 02 April’14

228

Case Report

A Rare case of Subcutaneous Mycosis due to Rhizoctonia  solani

Sahu. S1, Padhy .S2, Dash.M3, Mohanty.I4, Pattnaik.S5

Introduction:
Rhizoctonia solani  (R.solani)   is the most common-
ly identified species of Rhizoctonia. It is a soil borne
pathogen with a great diversity of host plants. It was
described by Julius Kuhn  on potato in 1858.It is a
basidiomycete fungus that does not produce any
asexual spores. In nature, it reproduces asexually
and exists primarily as vegetative mycelium and/or
sclerotia1.The vegetative mycelium of Rhizoctonia
solani are colorless when young but become brown
colored as they grow and mature.The key to identify
R.solani are  characteristics of its septate hyphae
branching at 90? angles ,constrictions at the base of
the hyphal branching sometimes with anastomosis
and clear  white , darkbrown to black colored
colonies on SDA. It can be able to survive for
extended periods of time in the absence of   living
host plants by feeding on decaying organic mat-
ter2.To the best of our knowledge this is the first
ever case of human subcutaneous mycosis due to
Rhizoctonia solani reported from south odisha.

Case report:
A 52 year old female agricultural  worker by profes-
sion came with a complaint of  progressive swelling
over the upper part of left leg  for the past 3 months
.It is a single circular swelling of size 6x5 cm pres-
ent on the anterior part of the left leg extends up to
lower border of patella . It extended medial and lat-
eral compartments slightly.Skin over the swelling
was normal without any inflammatory signs.No vis-
ible veins,pulsations ,sinus or any discharge  from
the swelling were seen .On palpation there was  no
local 
rise of temperature ,no tenderness  and skin over the
swelling was pinchable. All the borders were well
defined  and it was soft in consistency. There was no
restricted joint mobility.

There was a history of trauma while working in the
paddy field.On general examination all the vitals
were normal. She had mild pallor.The patient was
diabetic but not hypertensive. Pus was aspitated
under aseptic  conditions  and sent to the department

Correspond to: Dr.Susmita Sahu, Department of Microbiology M.K.C.G Medical college, Berhampur
Odisha PIN- 760001 e-mail: susmitakumarisahu@gmail.com

Abstract:
Rhizoctonia solani is a very common soil borne pathogen with a great diversity of host plants. 
A 52 year old lady presented with sole manifestation of subcutaneous swelling over the left leg 
for 3 months Pus was collected by aspiration revealed septatate fungal hyphae. After culture on 
SDA at 25 C showed white cottony growth initially, progressed to buff colored to black 
colonies on further incubation. On LPCB mount we found septate hyphae with acute and right 
angled branching with out any conidia and hyphal anastomosis which resembled features of 
Rhizoctonia solani. Patient was put on Fluconazole and responded well to the treatment.

1. Sahu. S, Senior  resident,  M.K.C.G Medical college
2. Padhy .S, Assistant  professor,  M.K.C.G Medical  college
3. Dash.M , Assistant professor,  M.K.C.G Medical  college
4. Mohanty.I , Senior resident,  M.K.C.G Medical college
5. Pattnaik.S, Junior  resident, M.K.C.G Medical college

Department of Microbiology; M.K.C.G Medical college Berhampur, Odisha, India.

DOI: http://dx.doi.org/10.3329/bjms.v13i2.15060
Bangladesh Journal of Medical Science Vol.13(2) 2014 p.228-230



of microbiology for examination. It was  thick  and
brown in colour without any odour on gross exami-
nation .Gram stain of the pus revealed few number
of  pus cells with septate hyphae. Basing on the pre-
liminary staining report  pus sample was inoculated
into SDA (Sabourauds dextrose agar) slants incubat-
ed at 25?C and 37?C . After 5 days of incubation at
25?C cottony white growth was appeared which
later turned tan to black colored starting from the
periphery  of the media.  On further incubation.The
whole colony turned  dark black coloured .The
reverse side showed white to grey colour  LPCB
mount of the colony showed septate hyphae without
conidia.The hyphae showed right angled branching
hyphae at some places fused together to form anas-
tomosis .This was identified as Rhizoctonia solani
basing on above features.Patient was put on oral
Fluconazole and the whole pus was drained. The
patient was discharged with advice for follow up in
out patient department.

Discussion:
Rhizoctonia solani belongs to  the   Phylum
Basidiomycota,class Agaricomycetes, order
Cantharellales,Family ceratobasidiaceae and genus
Rhizoctonia2 .It usually exists in nature as vegetative
mycelium and does not produce any asexual spores.
It consists of hyphae partitioned into individual cells
by septum containing small pore through which
movement of cytoplasm, mitochondria and nuclei
from cell to cell occurs.The hyphae branch often
branch at a 900 angles and usually possess more than
three nuclei per hyphal cells. The branched hyphae is
sometimes slightly constricted at the origin.They
produce sclerotia which are resistant to variation in
environmental conditions. These above features dif-
ferentiate R.solani from other Rhizoctonia fungi.
R.solani grows on potato dextrose agar and forms
grey to black colored colonies at the temperature
range of 18-280 .Sclerotia are produced on the sur-
face of cultures after 4 to 6 six weeks of  incubation2.

In 1969, J.R Parmeter and his colleagues reintro-
duced the concept of ‘hyphal anastomosis’ to charac-
terize and identify Rhizoctonia.This includes that the
isolates of Rhizoctonia which have the ability to rec-
ognize and fuse with each other are genetically relat-
ed,where as isolates that do not have this ability are
genetically unrelated3,4.This hyphal anastomosis cri-
teria have been extensively used to place isolates of
Rhizoctonia into taxonomically distinct groups .It is

grouped into 13 anastomosis groups (AG)  that vary
in pathogenecity,physical characsteristics and
sequence variations5. It is the method of genetic
recombination in Rhizoctonia.
It causes wide range of commercially significant
plant diseases ,but reports of human diseases caused
by it are very rare6. Till now  two cases of  human
mycosis due Rhizoctonium solani causing Keratitis7

and extensive mycosis2 were reported. 
In this case the patient was a  agricultural field work-
er and gave the history of trauma while working in
the field.This might be the cause of infection by pen-
etration of soil pathogen through the injury.Also the
patient is a known diabetic which helped the
pathogen to grow at the site of injury. To conclude
,R.solani is a well known plant pathogen and very
rarely causes human infection.This case was report-
ed because of its rarity.

Figure-1: Subcutaneous swelling on left leg.

Figure-2: Gram staining of pus sample showed
septate branched hyphae

Subcutaneous Mycosis due to Rhizoctonia  solani

229



Reference:

1. Paulo ceresini Pathogen profile created by course PP-
728 Soil borne plant pathogens,offered on spring1999

2. Kaore NM,Atul AR,Khan MZ,Ramnani VK. A rare
case of human mycosis by Rhizoctonia solani.Indian J
Med Microbiol 2012; 30:361-3.
http://dx.doi.org/10.4103/0255-0857.99508

3. Anderson NA.The Genetics and Pathology of Rhizoctonia
Solani. Annu Rev Phytopathol 1982; 20:329-47.
http://dx.doi.org/10.1146/annurev.py.20.090182.001553

4. Gracia VG,Onco MAP,Susan VR.Review,Biology and
Systematics of the form genus Rhizoctonia.Span J
Agric Res 2006;4:55-79.

5. Foley RC,Gleason CA,Anderson JP,Hamann T,Singh
KB(2013). Genetic and Genomic analysis of
Rhizoctonia solani Interactions with
Arabidopsis;Evidence of Resistance mediated through
NADPH oxidases.PLOSONE 8(2):e56814 doi
:10.137/journal.pone.0056814.

6. Manisha K,Panwar N.Morphological effects of Isolated
fungal specis on Human
p o p u l a t i o n . 1 : 5 2 1 . d o i : 1 0 . 4 1 7 2 / S c i e n t i f i c
reports.521.2012;1:1-6.

7. Srivastava OP,Lal B,Agarwal PK,Agarwal SC,Chandra
B,Mathur IS.Myotic keratitis due to Rhizoctonia
sp.Sabouraudia 1977;15:125-31.
http://dx.doi.org/10.1080/00362177785190201

Sahu. S, Padhy .S, Dash.M, Mohanty.I, Pattnaik.S

230

Figure-3: Growth of Rhizoctonia after 12 days on
SDA agar.

Figure-3: Fig 4 LPCB mount from slide culture
showing right anglebranching and anastomosis


