Malakoplakia

Updated: Jan 19, 2016
  • Author: Amira M Elbendary, MBBCh, MSc; Chief Editor: William D James, MD  more...
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Overview

Background

Malakoplakia is a rare granulomatous disease of infectious etiology. The name is derived from the Greek malakos (soft) and plakos (plaque), describing its usual clinical presentation as friable yellow soft plaques.

It was first described by von Hansemann in 1901 and in 1902 by Michaelis and Gutmann. [1]

Malakoplakia is most frequently reported to occur in the genitourinary system. The first case of malakoplakia reported to occur outside the genitourinary system was in 1958. [2] Since then, various organs have been reported to be affected.

Cutaneous malakoplakia is rare and was first reported in 1972 by Leclerc and Bernier. [3]

Malakoplakia is usually reported in the setting of immunocompromise, although rare reports in immunocompetent individuals have been documented.

Malakoplakia presents clinically with a wide spectrum of findings, and the criterion standard for diagnosis is pathological examination.

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Pathophysiology

Malakoplakia is believed to result from the inadequate killing of bacteria by macrophages or monocytes that exhibit defective phagolysosomal activity. Partially digested bacteria accumulate in monocytes or macrophages and lead to the deposition of calcium and iron on residual bacterial glycolipid. The presence of the resulting basophilic inclusion structure, the Michaelis-Gutmann body, is considered pathognomonic for malakoplakia. See the image below.

Michaelis-Gutmann body in a patient with malakopla Michaelis-Gutmann body in a patient with malakoplakia.

Studies have suggested that a decreased intracellular cyclic guanosine monophosphate (cGMP) level may interfere with adequate microtubular function and lysosomal activity, leading to an incomplete elimination of bacteria from macrophages and monocytes.

The incidence of malakoplakia in immunocompromised states, including post organ transplantation, diabetes mellitus, AIDS, malignancy, and immunosuppressive therapy, suggests that a disturbed function of T lymphocytes may play a role in the pathogenesis of malakoplakia in patients in states of immunocompromise. [1]

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Epidemiology

Frequency

The total number of patients with malakoplakia is fewer than 500. Most patients have genitourinary tract disease, although involvement of the gastrointestinal tract and other visceral organs has been described. Cutaneous malakoplakia is rare, with fewer than 50 cases reported in the literature. Because this disease is often diagnosed after biopsy of nondescript lesions, the true incidence is most likely higher.

Race

Cutaneous malakoplakia is more commonly reported in whites (39%) than in African Americans (19%) or Asians (12%), although the patient's ethnic group is often not specified in case reports.

Sex

Cutaneous malakoplakia occurs with a male-to-female ratio of 2.3:1.

Age

Cutaneous malakoplakia presents in patients with a broad age range. The median age at the time of presentation is 53 years. Occurrence of the disease is associated more with the presence of an immunocompromised state affecting monocyte and macrophage function than with age.

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