Sam questions uscap long Course 2016



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SAM Questions
USCAP Long Course 2016
Robinson- How to Diagnose the Most Common Odontogenic and Fibro-Osseous Lesions of the Jaws.



  1. A corrugated, keratinized epithelium that also shows parakeratosis and a palisaded basal layer in a cyst from the jaw most likely represents:

  1. Hyperplastic dental follicle

  2. Radicular cyst

  3. Unicystic ameloblastoma

  4. Dentigerous cyst

  5. Keratocystic odontogenic tumor

ANS. E) Keratocystic odontogenic tumor.

Keratocystic odontogenic tumor is benign cystic neoplasm that can have an aggressive course if not eradicated. It has very distinct histologic characteristics including a palisaded basal layer with the basal-most cells oriented along their long axis perpendicular to the basement membrane. The surface of the cyst lining is usually corrugated and there is always parakeratosis in the uppermost keratin layer.

While radicular cyst, dentigerous cyst and even ameloblastomas can show keratinization, none have this exclusive combination of these other histologic findings as seen in keratocystic odontogenic tumor.





  1. It is important from a treatment standpoint to separate unicystic ameloblastoma from other ameloblastomas with cystic changes. The key feature distinguishing unicystic ameloblastoma from other ameloblastomas with cystic changes is:




  1. Presence of a basal layer with reverse nuclear polarity in unicystic ameloblastoma

  2. Presence of stellate reticulum in unicystic ameloblastoma

  3. Absence of keratinization in unicystic ameloblastoma

  4. Absence of epithelial penetration of the cyst wall in unicystic ameloblastoma

  5. Absence of epithelial atypia in unicystic ameloblastoma when compared to other ameloblastomas

ANS D) Absence of epithelial penetration of the cyst wall in unicystic ameloblastoma


Unicystic ameloblastomas can be treated with a much less aggressive treatment plan than other ameloblastomas. While ameloblastomas can have cystic change, unicystic ameloblastoma is characterized by a cyst that is lined with epithelium that is normally found in ameloblastomas, including features of reverse nuclear polarity of the basal layer, stellate reticulum and frequent foci of keratinization. The one feature that must not be present in a unicystic ameloblastoma, no matter how cystic the lesion, is penetration of the ameloblastomatous epithelium into the wall of the cyst. If this is the case, the clinical course and hence treatment, will be that of usual ameloblastoma.


  1. When comparing fibrous dysplasia and cemento-ossifying fibroma, which of the following is NOT associated with fibrous dysplasia?

  1. Presence of a distinct capsule

  2. Fibrous connective tissue

  3. Woven bone production

  4. GNAS mutations

  5. Dysplastic bone fusing with normal bone at the periphery of the lesion

ANS: A) Presence of a distinct capsule


Fibrous dysplasia is an abnormality of bone formation and is associated with GNAS mutations. It, along with cemento-ossifying fibroma both have fibrous connective tissue components and woven bone production. However, a good way to separate the two lesions is to observe the peripheral portions of the lesions. Fibrous dysplasia is not a true neoplasm and the bone trabeculae that are seen in this process actually fuse with the surrounding bone at the periphery. On the other hand, cemento-ossifying fibroma is considered a true neoplasm and this is evidenced in part by its distinct delineation by a capsule which separates it from the surrounding bone, an observation that is noted both radiographically as well as histologically.


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