By Gary M. White, MD
Malakoplakia ("soft plaque") is a rare granulomatous disease in which a defect of the killing capacity of macrophages after endocytosis is considered to be the central event.
The majority of subjects are immunodeficient patients, including HIV-infected patients, patients with neoplasia, transplanted patients and others. Previously healthy patients with malakoplakia have been reported. The peak age is between the sixth and seventh decades, with rare cases in children.
Approximately 90% of patients have coliform bacteria detected in urine, blood, or tissue, suggesting an infectious cause. The most commonly found bacterium is Escherichia coli, but Klebsiella, Proteus, Pseudomonas, Mycobacterium avium, Mycobacterium tuberculosis, Shigella, Staphylococcus aureus and Enterococcus are also found. Most cases affects the genitourinary tract, but other systems have been implicated, including the skin.
The presentation varies greatly. Lesions are most commonly flesh-colored papules, plaques, nodules, and tumors. Diagnosis is usually made histologically.
Histopathologically, the pathognomonic finding is the Michaelis-Gutmann body, which represent partially degraded bacterial organisms. Michaelis-Gutmann bodies are intracytoplasmic, round-ovoid, basophilic, concentric laminated inclusions in macrophages that are typically enlarged and display foamy cytoplasm and eccentric, hyperchromatic, round nuclei, denoted as Hansemann cells.
No deaths have been related to malakoplakia, but death may occur due to the underlying condition. An infectious disease expert should be consulted. Antibiotics that concentrate in the macrophage such as ciprofloxacin or sulfamethoxazole-trimethoprim are recommended. Surgery may be done. Reducing immuosuppression if possible is helpful.
An. Bras. Dermatol. vol.88 no.3 Rio de Janeiro May/June 2013
A 45-year-old female with painful a cutaneous lesion in the genital area for 2 months and fever for 5 days. The patient had undergone a successful kidney transplant 2 years ago and was on immunosuppressant drugs (azathioprine 100 mg h.s. and prednisolone 20 mg OD) since then. A single, well-defined, indurated, tender, yellow plaque measuring 8 × 3.5 cm, with a granulomatous base and a few bleeding points was present on the surface of the left labia majora. Indian J Dermatol Venereol Leprol 2017;83:584-6