Dear Editor,
A previously healthy caucasian woman, 54 years old, came to dermatology outpatient
clinic with an erythematous nodulocystic lesion, about 2 cm, with no drainage ostium,
located on the dorsal surface of the 4th finger; associated with pain, edema and warmth
(Fig. 1). The injury arised four days after local trauma while cleaning her home bathroom.
She denied fever, or systemic symptom. There was no improvement despite the use of
oral antibiotics and corticosteroids. The hypothesis of pheohyphomycosis, sporotrichosis
and atypical mycobacteriosis were considered. Biopsy of the lesion and culture of
the liquid content were performed. The anatomopathological analysis showed an organized
chronic inflammatory process, occupying the entire thickness of the dermis, but without
the presence of fungi and acid-fast bacilli – AFB (Fig. 2). Mycobacterium fortuitum
was isolated from sample culture on Middlebrook 7H12. Serologies for HIV, hepatitis
B and C, and syphilis were all negative. After confirmation of the etiologic agent,
treatment with clarithromycin (1 g/day) and levofloxacin (1 g/day) was implemented,
with posterior change of this last medication to sulfamethoxazole-trimethoprim (1200 mg/240 mg
every 12 h), due to gastrointestinal intolerance, leading to complete regression of
lesion after 6 months (Fig. 3).
Figure 1
Right hand: edema and erythema on the fourth finger.
Figure 2
Chronic and organized inflammatory process, without detection of acid-fast bacilli
and fungi (Hematoxylin & eosin, ×40).
Figure 3
Regression of inflammation after antibiotic treatment.
Atypical mycobacteria, also known as MOTT (mycobacteria other than tuberculosis),
are acid-fast bacilli with slow growth in culture and very peculiar behavior. MOTT
may be saprophytic or found in animals, water and moist places. Atypical mycobacterioses
correspond to 10% of mycobacterial infections and preferentially affect immunocompromised
individuals.
1
The rapidly growing mycobacteria (RGM), known by their one-week culture growth, can
be found in various sites. The most relevant species are: M. fortuitum, M. chelonae,
and M. abscessus. M. fortuitum is related with hospital infections in immunocompromised
patients, leading to pulmonary, soft tissue and bone infections. Cutaneous involvement
is more related to postoperative situations and invasive cosmetic procedures.
2
The present case corresponds to cutaneous infection by M. fortuitum in an immunocompetent
patient, acquired at home, probably by a trauma in an humid area. Differential diagnosis
is made with swimming-pool granuloma, caused by M. marinum, due to the circumstances
in which the infection was acquired, but culture allowed to the definitive etiology.
The diagnosis of atypical mycobacterioses is made through the isolation of the agent
in culture, since radiological, histopathological and clinical examinations are often
inconclusive. The history of long-standing infection, without improvement after different
treatments, can lead to clinical suspicion. The follow-up includes long-term broad-spectrum
antibiotic treatment. The macrolide group in combination with quinolones is one of
the most recommended regimens, sometimes requiring surgical intervention.3, 4 The
present report reinforces the importance in considering atypical mycobacterioses among
the differential diagnoses of traumatic cutaneous lesions, especially when they tend
to chronicity.
Authors’ contributions
Dimitri Luz Felipe da Silva: Approval of the final version of the manuscript; conception
and planning of the study; elaboration and writing of the manuscript; obtaining, analysis,
and interpretation of the data; critical review of the literature; critical review
of the manuscript.
Letícia dos Santos Valandro: Conception and planning of the study; critical review
of the literature.
Paulo Eduardo Neves Ferreira Velho: Intellectual participation in the propaedeutic
and/or therapeutic conduct of the studied cases.
Andréa Fernandes Eloy da Costa França: Approval of the final version of the manuscript;
elaboration and writing of the manuscript; intellectual participation in the propaedeutic
and/or therapeutic conduct of the studied cases.
Financial support
None declared.
Conflicts of interest
None declared.