Pathology of Pindborg Tumor -
(Calcifying Epithelial Odontogenic Tumor)
Calcifying Epithelial Odontogenic Tumor (Pindborg tumor) is a rare, benign odontogenic lesion that accounts for less than 1% of all odontogenic tumors. I have highlighted 8 important features of this unique lesion.
8 Fast Facts :
(1) History: This is a rare benign odontogenic tumor which was first described in 1955 by Dutch pathologist Dr J J Pindborg. This tumour was later named Pindborg tumor by Shafer et al. In 1967, Abrams and Howell described the first case of CEOT predominantly composed of clear cells.
(2) Age and Sex: The tumour is most common in patients between 30 and 50 years of age, with no gender predominance.
(3) Clinical presentation: The tumor presents as slow-growing asymptomatic lesion in the posterior mandible of adult patients. It is a locally invasive swelling.
(4) Radiology: They appear either as monocystic or polycystic radiolucent lesions with radiopaque spots or masses, and also exhibit peripheral destruction with displacement of cortical bone and teeth.
(5) Microscopic features:
The tumour is characterized by cords and nests of round to polygonal eosinophilic cells set in a fibrous stroma.
There are distinct epithelial cellular outlines and presence of intercellular bridges. Nuclei show considerable variation and giant nuclei may be seen with nuclear pleomorphism. This nuclear pleomorphism is not considered to indicate malignancy.
Rounded masses of tumour amyloid are present.
There is scattered calcifications within the tumors. Calcification develop within amyloid-like materials and form concentric rings (Liesegang ring calcifications) , which tend to fuse to form large, complex masses.
These amyloid-like materials stain positively with Congo red or thioflavine T. After Congo red staining, amyloid exhibits an apple-green birefringence in polarized light.
Clear cell variant is characterized by nests of pale, uniform, clear cells with dark-stained nuclei.
Tumor cells are immunopositive for different subtypes of cytokeratins, Cytokeratins: AE1/AE3, CK7, CK8, CK13, CK14, CK19 and negativity for CK10 and CK20. CEOT with clear cells might also be positive for CD1a and negative for S-100, muscle specific actin, desmin, and antihuman melanosome.
(6) Differential Diagnosis:
The microscopic differential diagnosis of calcifying epithelial odontogenic tumor predominantly composed by clear cells include central mucoepidermoid carcinoma, metastatic malignancies originating from kidney, thyroid, and lung, or other odontogenic tumors such as ameloblastoma and clear cell odontogenic carcinoma.
(7) Types and variants
- Intraosseous lesion (tumour within the bone- central type) in the majority of cases (95%).
- Extraosseous or peripheral lesions account for fewer than 5% of cases It can be associated with an impacted tooth and radiographically simulate a dentigerous cyst. Most CEOTs are solid masses, and rarely show cyst spaces.
Several variants may appear with clear cell focal areas, cementum-like components, abundant Langerhans cells, combined epithelial odontogenic tumor (adenomatoid odontogenic tumor), and abundant myoepithelial cells.
Maxillary CEOTs are usually more aggressive and spread more rapidly to possibly involve surrounding vital structures than mandibular tumours. Maxillary lesion should be treated more aggressively, and five years is considered the absolute minimum follow-up period.
Lee SK, Kim YS. Current Concepts and Occurrence of Epithelial Odontogenic Tumors: II. Calcifying Epithelial Odontogenic Tumor Versus Ghost Cell Odontogenic Tumors Derived from Calcifying Odontogenic Cyst. Korean Journal of Pathology. 2014;48(3):175-187.
Turatti E, Brasil J, de Andrade B-A-B, Romañach M-J, de Almeida O-P. Clear cell variant of calcifying epithelial odontogenic tumor: Case report with immunohistochemical findings . Journal of Clinical and Experimental Dentistry. 2015;7(1):e163-e166.
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