Malakoplakia Involving the Maxilla: A Case Report and a Review of the Literature.

Malakoplakia is a rare inflammatory disorder which typically occurs in immunocompromised patients secondary to impaired bactericidal activity of macrophages. While this entity commonly arises in the genitourinary and gastrointestinal tracts, lesions of the head and neck have been reported only rarely, with oral cavity involvement reported in 3 cases. The most common presentation of head and neck malakoplakia is that of a cutaneous flesh-colored papule or nodule. This case report, however, illustrates the first time malakoplakia is identified affecting the maxilla and maxillary alveolar ridge mucosa. Histochemical and immunohistochemical stains are presented and include positivity for PAS, von Kossa stain, iron stain, and CD68 and negativity for GMS and Gram stains, indicating an inability to demonstrate microbial infection. Thus, clinicians and pathologists alike should be aware of malakoplakia as a pathologic entity when forming differential diagnoses, particularly in immunosuppressed individuals.

CD1a is not effective in distinguishing calcifying epithelial odontogenic tumors from amyloid-rich central odontogenic fibroma.

OBJECTIVE: Differential diagnosis between the non-calcifying variant of calcifying epithelial odontogenic tumor (NCLC-CEOT) and amyloid-rich central odontogenic fibroma (AR-COdF) has become a debate, particularly regarding the frequency of CD1a positivity in both entities. This has led to the growing consensus that CD1a-positive staining in AR-NC lesions confirms the diagnosis of AR-COdF. Here, we assess the validity of this consensus. STUDY DESIGN: We collected the data of a case series of histopathologically distinct CEOTs, NCLC-CEOTs, and COdFs and stained them for CD1a and amyloid. Of the 9 CEOTs and NCLC-CEOTs, we diagnosed 4 as classic, 3 as associated with a dentigerous cyst, and 2 as combined CEOT/adenomatoid odontogenic tumors. Of the 9 COdFs, we diagnosed 3 as epithelial poor, 3 as epithelial rich (lacking amyloid), 2 as hyalinized with amyloid, and 1 as hyalinized without amyloid and assessed the staining results. RESULTS: Of the 9 CEOTs and NCLC-CEOTs, 7 stained positively for CD1a, 5 diffusely and 2 focally. Notably, 2 classic NCLC-CEOTs stained strongly CD1a positive. All 3 of the epithelial-poor COdFs were predictably CD1a negative. Of the 6 remaining COdFs, 2 were CD1a positive, 1 hyalinized-with-amyloid COdF diffusely and 1 epithelial-rich-without amyloid focally. CONCLUSIONS: CD1a positivity, which occurs in classic CEOT and NCLC-CEOT, does not help distinguish between NCLC-CEOT and AR-COdF and is inconsistent in all AR-COdFs. The diagnosis of CEOT and AR-COdF should be guided by appropriate histopathologic criteria irrespective of CD1a staining or the presence of amyloid or calcifications.