Pseudoameloblastomatous Changes in
the Wall of a Radicular Cyst
MARSHALL
P.
SOLOMON,
D.D.S., J.
WILLIAM BRIDBORD,
AND Y A L E R O S E N ,
D.D.S.,
M.D.
Departments of Pathology and Oral Surgery, State University of New York, Downstate Medical Center and State University
Kings County Hospital Center, Brooklyn, New York
ABSTRACT
Solomon, Marshall P., Bridbord, J. William, and Rosen, Yale: Pseudomeloblastomatous changes in the wall of a radicular cyst. Am. J. Clin. Pathol. 61:
443-446, 1974. A periapical soft-tissue lesion from a maxillary bicuspid root tip
was studied histologically. The initial impression was plexiform ameloblastoma. Subsequent review of the radiographic appearance of the lesion and
tissue sections from deeper within the paraffin block revealed a cystic structure.
The cyst was lined by squamous epithelium, and a marked chronic
inflammatory infiltrate was found in the wall. There were foci of hyperplastic
squamous epithelium originating from the cyst lining and proliferating into the
wall. A descriptive diagnosis for this variant of a radicular cyst is presented.
(Key words: Pseudoameloblastoma; Ameloblastoma; Radicular cyst; Teeth;
Odontogenic cyst.)
THE
INTERRELATIONSHIP
between
ameloblastomas and the epithelial linings
of odontogenic cysts has been well documented. 1,5 ' ? Follicular cysts in particular have been rigorously investigated, 1,5,7
reviewed and noted as potential sites of
origin of ameloblastomas. However, the
epithelial linings of radicular cysts have
rarely been shown to be a source of
ameloblastomas. 2 Some cases of "residual
cysts" have been shown to have ameloblastomatous potential. Unfortunately, in
many of these cases the exact gross
pathologic anatomy of these cysts (i.e.,
anatomic relationship of cyst to dental
structures) cannot be demonstrated. 3,6
Therefore, we do not know whether these
residual cysts are follicular or radicular.
Diagnosis is further complicated by occasional problems in microscopic diagnosis of
Received August 13, 1973; accepted for publication
September 20, 1973.
443
FIG. 1. Roentgenograph demonstrating wellcircumscribed unilocular radiolucency at the apex of
the root of the left maxillary second bicuspid (arrow).
these cystic lesions. T h e following case
report illustrates a diagnostic problem
occuring in a radicular cyst.
444
SOLOMON ET AL.
A.J.C.P.—Vol.61
FIG. 2 (upper). Fibrous capsule (arrows) surrounds the lesion. Proliferation of epithelial cells arranged in an
anastomosing pattern is suggestive of the dental lamina of odontogenesis. Hematoxylin and eosin. x 15.
FlG. 3 (lower). Higher magnification of one of the segments in Figure 2.
Hematoxylin and eosin. x 50.
Report of a Case
A 22-year-old Negro man was admitted
to Kings County Hospital for a suspected
peptic ulcer. His condition was being
controlled by diet. Upon complaint of
intraoral pain, T h e Department of General
Surgery referred the patient to T h e
Department of Oral Surgery. Intraoral
examination showed rampant caries with
periodontal complications. There was a
slight protuberance of the alveolar mucosa
March 1974
PSEUDOAMELOBLASTOMATOUS CHANGE
445
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FIG. 4 (upper). Anastomosing strands bordered by a single layer of plump squamoid cells surrounding
areas of stellate cells. Hematoxylin and eosin. x 400.
FIG. 5 (lower). Cyst with squamous epithelial lining, showing foci of hyperplastic squamous epithelium proliferating into the wall. Note occasional zones of chronic inflammation. Hematoxylin and eosin. x 50.
with a pointing fistula in the region of the
maxillary left second bicuspid. The lesion
was firm, with slight tenderness over the
fistula. No purulence was noted.
Panorex x-ray examination revealed a
well circumscribed unilocular radiolucency
at the apex of the root of the left maxillary
second bicuspid (Fig. 1).
The patient was a poor historian and
could not be certain of the duration of the
lesion. Past medical history revealed infectious hepatitis as an adolescent.
446
SOLOMON ET AL.
Under local anesthesia, a firm, greycolored soft-tissue mass attached to the
maxillary left second bicuspid root was
removed. No other tissue in the alveolus of
the maxillary left second bicuspid could be
seen clinically, and it was felt that this
represented the entire lesion. The impression at the time of operation was radicular
cyst secondary to an infected root tip.
The specimen, still attached to the tooth,
was submitted for routine pathologic
examination.
Immediate Postoperative Course. T h e patient was seen five days later for suture
removal, after having been discharged
from the hospital. All operative areas were
healing well and the patient reported no
discomfort. A month postoperatively, the
region of the soft-tissue lesion showed
normal uncomplicated extraction-wound
healing. Subsequently the patient was lost
to follow up.
Gross Specimen. T h e specimen consisted
of a well demarcated nodule of soft tissue
measuring 3.0 X 1.0 X 0.4 cm. attached to
the apex of a bicuspid root. T h e soft tissue
was separated from the root a n d
hemisected. On cut section, the tissue was
found to be solid. Both hemisected
segments of soft tissue were embedded.
Microscopic Examination. T h e lesion was
well demarcated and surrounded by a
fibrous capsule. Within the fibrous capsule
there were proliferating epithelial cells
arranged in an anastomosing pattern
suggestive of the dental lamina of odontogenesis. (Fig. 2). T h e anastomosing
strands were bordered by a single layer of
plump squamoid cells surrounding an
internal area of stellate cells. The stroma
was edematous and contained several foci
of chronic inflammation. No lumen was
seen. (Figs. 3 and 4).
At this point, the diagnosis of ameloblastoma was considered on the basis of
histopathologic morphology alone. Upon
review of the radiographic appearance of
the lesion, it was decided to prepare
additional sections from the remaining
A.J.C.P.—Vol.
61
tissue embedded in the paraffin block.
Sections from deeper within the tissue
block were examined, and these revealed a
cystic lesion lined by squamous epithelium
with a marked chronic inflammatory
infiltrate in the cyst wall. Many areas of the
cyst wall showed foci of hyperplastic
squamous epithelium originating from the
cyst lining and proliferating into the wall.
These proliferations were often seen in
zones of extensive chronic inflammatory
infiltrate (Fig. 5). These observations led us
to the conclusion that the nature of the
lesion was inflammatory, 4 specifically, a
radicular cyst with nonneoplastic changes
in the epithelial lining secondary to chronic
inflammation. The source of the chronic
inflammation was the severely decayed
remnants of the maxillary left second
bicuspid, with the pulp canal of the tooth
acting as a pathway of infection.
Discussion
In some chronically inflamed odontogenic cysts (e.g., follicular, radicular),
anastomosing strands of epithelium may
penetrate deep into the connective tissue
wall.4 Morphologically these lesions may
superficially resemble a plexiform type of
ameloblastoma. However, the cells at the
periphery of the strands of epithelium in a
true ameloblastoma are often cuboidal or
columnar. While some of the peripheral
cells of a plexiform ameloblastoma may be
squamoid or flat, it is rare not to see any cells
in a section demonstrating cuboidal or
columnar traits.
In the above case, these cells are of a
definite squamoid character, arranged in a
pattern resembling the plexiform ameloblastoma. Plexiform ameloblastoma is
known to be locally invasive and poorly
demarcated at the periphery, whereas the
lesion being reviewed is well demarcated
and has a fibrous capsule.
Radiographically the appearance of this
lytic lesion is consistent with the diagnosis of
radicular cyst and not follicular cyst. As
March 1974
PSEUDOAMELOBLASTOMATOUS CHANGE
noted earlier, the occurrence of ameloblastomas in radicular cysts is rarely if ever
observed.
Considering the clinical, radiologic and
pathologic aspects of this lesion, the
descriptive diagnosis "pseudoameloblastomatous changes in the wall of a radicular
cyst" is suggested for this and similar cases.
Because of the wide differences in
biological behaviors and treatments of
ameloblastoma and radicular cysts, on the
one hand, and the occasional marked morphologic similarity of these two lesions on
the other, the importance of avoiding
misdiagnosing ameloblastoma in the variant of radicular cyst herein reported
cannot be overemphasized. T h e correlation
of morphologic, radiographic, and clinical
aspects of the lesion will minimize the
447
possibility of misdiagnosis in a case of this
typeReferences
1. Cahn LR: T h e dentigenous cyst is a potential
adamantinoma. Dent Cosmos 75:889-893,
1933
2. Carpenter LS, Thoma KH: Adamantinoma
formed from a radicular cyst. Dent Items
Interest 55:716-721, 1933
3. Lee FMS: Ameloblastoma of the maxilla with
possible origin in a residual cyst. Oral Surg Oral
Med Oral Pathol 29:799-805, 1970
4. Lucas RB: Ameloblastoma: Pathology of Tumors
of the Oral Tissues. Second edition. Boston,
Little, Brown, 1972, pp 46-48
5. Lucas RB: Neoplasm in odontogenic cysts. Oral
Surg 7:1227-1235, 1954
6. Small GS, Lattiner CW, Waldron CA: Ameloblastoma of the mandible simulating a radicular
cyst. J Oral Surg 16:231-235, 1958
7. Stanley HR, Diehl DL: Ameloblastoma potential of
follicular cysts. Oral Surg Oral Med Oral Pathol
20:260-268, 1965
Letters to the Editor
Activated Partial Thromboplastin Reagents
To the Editor:—We are commenting on
the article "Comparison of Activated Partial
Thromboplastin Reagents" (Sibley et al.,
Am J Clin Pathol April 1973).
Based on our experience over a sevenyear period of using APT V, we feel that a
result of 49.1 seconds with the normal
reference plasma and reagent APT V
should have been considered as the first
clue that a malfunction in the test system
might have existed. Our upper limit of
normal has never exceeded 46.0 seconds
regardless of test methodology. We also feel
that one set of assays for a single factor at
one day's testing time may not constitute an
adequate critique of reagents.
The use of the Fibrometer without
Received July 23, 1973; received revised manuscript
September 13, 1973; accepted for publication
September 18, 1973.
Key word: Thromboplastin.
special precaution for clot detection in
performing factor assays may have been a
major factor in the difficulty these investigators had in obtaining consistent results.
Many laboratory people are reluctant to use
a Fibrometer for reading particulate
activators. Furthermore, in the Sibley
investigation, two instrument systems and
two sets of probes were used by two
technologists. A different factor was assayed each day. With even one instrument,
the sources of error and irreproducibility
are legion.
At T h e Fairfax Hospital, Falls Church,
Virginia, 13 patients with abnormal APTT
(42-50 seconds) were assayed. Six were
found to have decreased Factor VIII levels
(22-^5%), and seven had decreased Factor
IX levels (25-50%). At T h e Ohio State
University Hospitals, Columbus, Ohio, 30
patients with abnormal A P T T (47-59