Case Report
A fast-growing cold skin abscess
revealing disseminated Mycobacterium
intracellulare infection in an
HIV-infected patient
Pedro Mendes-Bastos
1,2
, Susana Bra
´
s
1
and Rodrigo Carvalho
1,2
Abstract
A 66-year-old woman with HIV-1 infection recently commenced on antiretroviral therapy (CD4þ 25 cells/mm
3
was
referred to the Dermatology Clinic the following month due to a well-demarcated nodule in the extensor surface of the
left arm with evident fluctuation but only slight pain on palpation, with no increase in temperature. Surgical drainage was
performed with aspiration of yellowish-green exudate, with no characteristic smell. In culture of cutaneous exudate,
Mycobacterium intracellulare was isolated. Upon careful review of the laboratory tests that were in progress at discharge,
the same agent was isolated in one of the bronchoalveolar lavage cultures. The diagnosis of cutaneous abscess caused by
M. intracellulare from hematogenous dissemination of lung infection was made. The patient was treated with clarithro-
mycin, ethambutol and rifabutin for 24 months. M. intracellulare species and Mycobacterium avium constitute the
Mycobacterium avium–intracellulare complex (MAC), responsible for the majority of human infections by atypical myco-
bacteria. They are ubiquitous bacteria and MAC infection mainly affect immunocompromised patients, with M. intra-
cellulare being isolated in <5% of HIV patients with MAC infection. Cutaneous infection is rare and may present clinically
with erythematous plaques, chronic ulcers or abscesses. When present, skin involvement is usually secondary to
pulmonary infection.
Keywords
Mycobacterium avium–intracellulare infection, infectious skin diseases, human immunodeficiency virus
Date received: 20 August 2017; accepted: 21 November 2017
Case report
A 66-year-old female patient originally from Guinea-
Bissau was referred to the Dermatology Clinic due to a
fast-growing asymptomatic skin nodule on the left
arm, present for one week. Two months before,
she had been admitted to the Infectious Diseases
Ward for Pneumocystis jiroveci pneumonia and
Cytomegalovirus proctitis, revealing an undiagnosed
human immunodeficiency virus-1 (HIV-1) infection
(CD4þ cell count of 25 cells/mm
3
, viral load of
507,653 copies/mL). After appropriate medical treat-
ment and the start of tenofovir/emtricitabine and ralte-
gravir (TDF/FTC þ RAL), the patient became
asymptomatic and was discharged with residual lung
disease on CT scan.
On skin examination, a single well-demarcated and
non-ulcerated 4-cm diameter skin nodule on the
extensor surface of the left arm was observed
(Figure 1). There was fluctuation upon palpation but
no pain, warmness or redness (Figure 2). No lymph-
adenopathy was present and the patient denied any
local trauma. This skin abscess was surgically drained,
releasing an abundant odorless yellowish thick fluid
that was fully aspirated and sent for culture – aerobic
and anaerobic bacteria, fungi and mycobacteria. The
1
Department of Dermatology and Venereology, Centro Hospitalar de
Lisboa Central, Lisboa, Portugal
2
Dermatology Centre, Hospital CUF Descobertas, Lisboa, Portugal
Corresponding author:
Pedro Mendes-Bastos, Dermatology Centre, Hospital CUF Descobertas,
Rua Ma
´
rio Botas, Lisboa 1998-018, Portugal.
Email: pmendesbastos@gmail.com
International Journal of STD & AIDS
0(0) 1–3
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DOI: 10.1177/0956462417748240
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cystic cavity was repeatedly injected with a diluted
solution of povidone–iodine. Direct examination of
the skin exudate was negative, including for acid-fast
bacilli. Two weeks later, the skin nodule relapsed and
the procedure was repeated.
One month after the first surgical drainage,
Mycobacterium intracellulare was identified as the caus-
ative agent of the skin abscess (culture and nuclear
hybridization). At that time, the same agent was isolat-
ed from one sample of the bronchoalveolar lavage col-
lected three months before as an inpatient.
We made the diagnosis of a disseminated
M. intracellulare infection. The patient was kept on
TDF/FTC þ RAL in addition to clarithromycin
250 mg bid, ethambutol 1200 mg qd and rifabutin
300 mg qd for 24 months.
The skin nodule regressed after two weeks and com-
puted tomography of the thorax showed no residual
lung disease at nine months of therapy. After 24
months of therapy, the immune status had improved
(CD4þ cell count of 261 cells/mm
3
, viral load <20
copies/mL) and the antimycobacterial therapy was
stopped. No lung or skin recurrence occurred at six
months of follow-up.
Discussion
A global decrease in tuberculosis was accompanied by
an increased awareness of atypical mycobacteria (AM)
-associated disease.
1
Due to similar clinical, etiological
and antigenic similarities, some groups of AM are con-
sidered together as complexes: Mycobacterium avium
and M. intracellulare are grouped together as the
Mycobacterium avium–intracellulare complex (MAC).
The MAC complex agents are ubiquitous slow-
growing pathogens and environmental exposure is con-
sidered the pred ominant path way to disease. Regarding
cutaneous AM disease occurring globally, several
recent case series classify 65–86% of the affected
patients as immunocompetent.
2–4
MAC disease, on
the other hand, is much more common in immunosup-
pressed individuals, mainly in persons with advanced
HIV infection, and the more frequent clinical presenta-
tion is lung disease or disseminated disease.
1
Figure 1. A single well-demarcated and non-ulcerated 4-cm
diameter skin nodule on the extensor surface of the left.
Figure 2. Fluctuation upon palpation was evident, with no pain,
warmth or redness.
2 International Journal of STD & AIDS 0(0)
Disseminated AM disease in HIV patients is due to
MAC in >90% of cases, with more than 90% of
those infections due to M. avium; it tends to occur in
patients who are severely immunocompromised, as evi-
denced by very low CD4þ T-cell counts.
5
Skin involvement revealing MAC disseminated disease
has been rarely reported, both in healthy and in immu-
nocompromised patients
6,7
and is not considered a typ-
ical clinical presentation.
1
According to most studies,
the importance of MAC in cutaneous AM disease is
limited. As most cases of cutaneous AM infection
occur in immunocompetent patients and are limited
to skin and soft tissues, other agents as
Mycobacterium marinum or Mycobacterium fortuitum
are much more commonly reported.
1,4,8
Primary cuta-
neous infection by MAC is rare, and excluding con-
comitant pulmonary disease is considered
mandatory,
9
especially in the context of immunosup-
pression. The variety of clinical manifestations is wide
and non-specific, including erythematous plaques,
ulcers and abscesses.
1,3,6,7,10
As a crucial part of multi-
disciplinary teams, the dermatologist is on the front
line of care for severely immunocompromised patients
and a high level of suspicion is mandatory when
approaching these cases.
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with
respect to the research, authorship, and/or publication of this
article.
Funding
The author(s) received no financial support for the research,
authorship, and/or publication of this article.
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Mendes-Bastos et al. 3
