Doctors Report Rare Case of Leishmaniasis Hidden in a Congenital Skin Defect
A woman in her 50s developed a painful, non-healing sore on her left buttock that was ultimately traced to an unusual interaction between a rare congenital abnormality and a parasitic infection. According to the treating physicians, this may be the first documented case of its kind.
For nearly two years, the patient lived with a draining lesion that repeatedly filled with fluid and required ongoing medical attention. Approximately 20 years earlier, she had experienced a similar lesion in nearly the same location, but that episode resolved spontaneously, leaving only a faint scar.
When she sought specialist care for the recurrent sore, clinicians diagnosed a parasitic infection caused by Leishmania, a genus of protozoan parasites transmitted to humans through the bites of infected sand flies. These parasites typically cause cutaneous ulcers that heal slowly and may leave cosmetically significant scars.
Although most immunocompetent individuals eventually clear cutaneous leishmaniasis, in this case the parasites found an unusually vulnerable anatomical niche. Imaging studies and surgical exploration revealed a congenital dermal sinus tract within the patient's buttock—a hidden channel beneath the skin that had been present since birth.
How the Hidden Defect Formed
A congenital dermal sinus is a developmental anomaly that occurs when the fetal skin and underlying neural tube fail to separate and close completely during early embryonic development. This incomplete closure can leave a narrow epithelial-lined tract extending inward from the skin surface.
These tracts most commonly occur along the midline of the back near the spine and may appear as a small dimple or shallow depression on a newborn's skin. Because they can serve as entry points for bacteria and other pathogens, they are often surgically removed when identified during infancy.
In this patient, however, the sinus tract was located on the lateral aspect of the buttock, an exceptionally rare location for this congenital anomaly. It remained clinically silent for decades, with only the earlier self-resolving lesion suggesting the presence of an underlying abnormality.
The authors of the case report note that although dermal sinus tracts involving the buttock have occasionally been described, leishmaniasis developing within such a tract has not previously been reported. This unusual combination created a protected anatomical channel in which the parasites were able to persist and cause chronic drainage.
Leishmaniasis and the Global Disease Burden
Leishmaniasis is classified by the World Health Organization as a neglected tropical disease and affects more than one million people worldwide each year. It is endemic in parts of Latin America, Africa, the Middle East, Asia, and southern Europe, with transmission closely associated with sand fly habitats and poverty-related living conditions.
Cutaneous leishmaniasis, the form diagnosed in this patient, primarily affects the skin and typically presents with slowly enlarging ulcers, nodules, or plaques at the site of the sand fly bite. Symptoms may persist for several months to more than a year, and although many lesions eventually heal spontaneously, permanent scarring is common.
A more severe form, visceral leishmaniasis, affects internal organs including the liver, spleen, and bone marrow. This systemic disease can cause prolonged fever, weight loss, anemia, and enlargement of internal organs and is frequently fatal without prompt treatment.
Leishmania parasites are known to exploit compromised or damaged skin, including burns, chronic wounds, and old scars. Research suggests that the parasites may persist within apparently healed tissues for prolonged periods, potentially contributing to recurrent disease and unusual clinical presentations in susceptible anatomical sites.
Treatment, Outcome, and Clinical Lessons
Fortunately, the patient had only cutaneous disease and timely access to specialist medical care. She was treated with antiparasitic medication to eliminate the Leishmania infection, followed by surgical excision of the congenital dermal sinus tract.
During surgery, the physicians confirmed that the sinus tract had no connection with the spinal cord or other critical anatomical structures, minimizing the risk of neurological complications. Complete removal of the tract eliminated the concealed pathway that had enabled the parasites to maintain the chronic lesion.
The patient recovered well following treatment. Her physicians emphasize that this case illustrates how congenital abnormalities, even when clinically silent for decades, can become focal points for rare infectious diseases. They recommend maintaining a high level of clinical suspicion in endemic regions when evaluating chronic skin lesions occurring near dimples, pits, or old scars.
With the patient's informed consent, the clinical team published the case in BMJ Case Reports to increase awareness among clinicians and public health professionals. They argue that recognizing such unusual presentations is essential for improving diagnosis, preventing complications, and advancing our understanding of how neglected tropical diseases exploit congenital anatomical vulnerabilities.
