Are You Confident of the Diagnosis?
Malacoplakia is a rare condition which is even more uncommon in the skin. Approximately 40 cases have been reported and the condition appears more common in men than in women. Malacoplakia, meaning “soft plaque” was initially described in the genitourinary tract. Most sites, including lung, gastrointestinal tract, and others have been reported. However, the genitourinary tract remains the most commonly reported site, representing 70% of the cases in the literature.
Characteristic findings on physical examination
Skin lesions are polymorphic and often not clinically suggestive. The primary feature associated with the diagnosis is growth and persistence of the lesions. Skin fold sites are favored as clinical sites. This often leads to malignancy as the primary differential diagnosis. In view of its rarity, consideration of the possibility of malacoplakia on the part of the physician is critical for achieving a correct diagnosis.
Expected results of diagnostic studies
The only consistently valuable test for the disease is biopsy for histology, where the features are very characteristic and may be diagnostic. The presence of Michaelis-Gutmann bodies is considered the key diagnostic feature.
Michaelis-Gutmann bodies are basophilic intracellular collections within periodic acid-Schiff (PAS)-positive macrophages that stain both with stains for hemosiderin (Prussian blue reaction or Perl’s stain) and stains to demonstrate calcium (Von Kossa stain). These bodies are thought to represent lamellated intracellular lysozomal granules in which unresorbed debris has functioned as a focus for calcification.
As noted above, pathology is diagnostic, but the rarity of the condition can lead to it not being considered even by practicing pathologists.
Who is at Risk for Developing this Disease?
Over 70% of reported case of cutaneous malacoplakia are associated with some form of systemic immunosuppression. The most common association has been renal transplantation. Other associations include:
–HIV infection with AIDS
Since rare case are reported in immunocompetent patients, the condition should be considered in the setting of a growing or persistent plaque in skin fold sites regardless of immune status.
What is the Cause of the Disease?
Malacoplakia is a form of granulomatous reaction believed to be related to diminished intracellular killing of bacterial organisms. The compromised immunity that is the primary setting of the condition leads to ineffective bacterial destruction within the macrophage and continued infection. In addition, the debris from the residual bacterial organisms remains as a focus for mineralization within the cell.
In the genitourinary tract, certain organisms appear to be most frequent as causes of the disorder, notably Rhodococcus equi. R equi is an actinomycete distantly related to the bacterium in Whipple’s disease. However, coliform bacteria and mycobacteria have also been associated with the condition.
Systemic Implications and Complications
Since malacoplakia is primarily associated with immunosuppression, the condition should be considered in the setting of a dark or reddish growing and persistent plaque, particularly in the groin, perianal region or in skin fold sites. Other sites are reported.
The work-up consists of biopsy for histology and culture. Mentioning the consideration in the pathology requisition will aid the pathologist in considering the entity and may lead to proper special stain workup of the case.
–Surgery for removal of the lesion
–Broad-spectrum antibiotics, notably quinolones. (ciprofloxacin or levofloxacin)
Optimal Therapeutic Approach for this Disease
If a lesion can be reliably and easily removed, surgery is the most consistently effective strategy. Quinolone antibiotics can be prescribed for lengthy treatment duration until lesions resolve. Prolonged treatment with ciprofloxacin 500mg orally twice daily may be needed; the time frame of therapy is variable, based on response. Consultation with an infectious disease specialist is warranted.
Since most cases are associated with immunosuppression, all patients should be evaluated for evidence of immune compromise. The history should identify patients with transplantation. HIV testing is indicated in patients without other indication of immune suppression. Serum calcium, serum angiotensin converting enzyme level and chest x-ray should suffice to evaluate for sarcoidosis in conjunction with clinical examination.
Unusual Clinical Scenarios to Consider in Patient Management
Immunosuppressed patients are at risk for both malacoplakia and carcinoma. It is important to identify patients who have both conditions.
What is the Evidence?
Lowitt, MH, Kariniemi, AL, Niemi, KM, Kao, GF. “Cutaneous malacoplakia:a report of two cases and review of the literature”. J Am Acad Dermatol. vol. 34. 1996. pp. 325-32. (Likely the best overall review of the disease, using two case reports to discuss this rare disease.)
Wittenberg, GP, Douglass, MC, Azam, M, Lee, MW, Al-Ujayli, B, Lowe, L. “Cutaneous malacoplakia in a patient with the acquired immunodeficiency syndrome”. Arch Dermatol. vol. 134. 1998. pp. 244-5. (Short case report of a patient with immunodeficiency that developed malocoplakia.)
Kohl, SK, Hans, CP. “Cutaneous malakoplakia”. Arch Pathol Lab Med. vol. 132. 2008. pp. 113-7. (Pathological review of cutaneous malocoplakia.)
Sarkell, B, Dannenberg, M, Blaylock, WK, Patterson, JW. “Cutaneous malacoplakia”. J Am Acad Dermatol. vol. 30. 1994. pp. 834-6. (Short case report and review of the literature.)
Almagro, UA, Choi, H, Caya, JG, Norback, DH. “Cutaneous malakoplakia:report of a case and review of the literature”. Am J Dermatopathol. vol. 3. 1981. pp. 295-301. (Case report and synopsis of the clinical and pathological findings.)
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