COM November 2009

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November 2009: Unilocular radiolucency around impacted tooth #22

Dolphine Oda, BDS, MSc
doda@u.washington.edu

Contributed by
Drs. Richard Day & Thomas Burkhardt
Southeast Alaska Pathology and Oral Surgery, Wasilla, AK

Case Summary and Diagnostic Information

This is an 11-year-old white female who was referred by her orthodontist for evaluation of a “cyst” associated with impacted tooth #22 (Figure 1).

Diagnostic Information Available

History of present Illness

This is an 11-year-old white female who was referred by her orthodontist for evaluation of a “cyst” associated with impacted tooth #22 (Figure 1). She was asymptomatic and was not aware of the lesion. Clinical examination revealed an expansion of facial cortex below teeth #s 21-25 with missing tooth #22 and retention of deciduous tooth # M.  No other clinical or neurological abnormalities were detected. The initial panoramic and lateral cephalic radiographs revealed a unilocular radiolucent lesion around the crown of a horizontally impacted #22 (Figure 1).  

Medical History

The patient’s past medical history is not significant.

Clinical and Radiographic Findings

This lesion was asymptomatic and was discovered by the patient’s orthodontist.  The clinical examination was significant for retained tooth #M, missing tooth #22 and expansion of the facial bone between teeth #21 and 25.  The radiographic features were as significant as the clinical examination, confirming the missing tooth being impacted (Figure 1), the retained tooth #M and the expansion being the result of a unilocular radiolucency around the impacted tooth #22. 

Figure 1 This is a panoramic view taken at the first clinical presentation. The radiograph demonstrates a well-demarcated to corticated unilocular radiolucency around impacted tooth #22 with the tooth displaced inferiorly.

Excisional Biopsy

Treatment

Under general anesthesia, an incision was made from approximately tooth #21 to tooth #25.  The mental nerve was retracted posteriorly and inferiorly.  The periosteum was carefully dissected off and the facial wall of the expanded area removed.  The lesion was then removed, as was the impacted tooth #22.  The cavity was copiously irrigated with saline solution and the rough and irregular margins smoothed.  The area was closed with chromic gut suture.  The area healed with no complications.

Incisional Biopsy

Histologic examination of the H & E section revealed multiple pieces of decalcified hard and soft tissue composed of a neoplasm of odontogenic epithelial origin and multiple tooth fragments representing sections of the impacted vital canine tooth.  The soft tissue component comprises the bulk of the specimen and is made up of a cystic structure with lining epithelium surrounded by connective tissue wall.  The lining epithelial is made up of spindle-shaped cells arranged in whorls and strands as well as lace-like structures (Figures 2 & 3).  The spindle epithelial cells are interspersed with duct-like structures lined by one layer of cuboidal epithelial cells (Figures 4 & 5). 

Figure 2 Low power (x40) histology shows an H & E stained section made up of a cystic structure with lining epithelium surrounded by connective tissue wall. The lining epithelial is made up of spindle shaped cells arranged in whorls and strands.

Figure 3 Higher power (100) histology shows an H & E stained section with a closer look at the spindle shaped epithelial cells arranged in whorls and strands.

Figure 4 Higher power (200) histology shows an H & E stained section with a closer look at the duct-like structures lined by one layer of cuboidal epithelial cells.

Figure 5 Higher power (200) histology shows an H & E stained section with a closer look at the many duct-like structures lined by one layer of cuboidal epithelial cells.

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