An enlarged sella turcica on cephalometric radiograph
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Dentomaxillofacial Radiology (2005) 34, 308–312
q 2005 The British Institute of Radiology
http://dmfr.birjournals.org
CASE REPORT
An enlarged sella turcica on cephalometric radiograph
H-P Chang*,1, Y-C Tseng2 and T-M Chou1
1
Faculty of Dentistry and Graduate Institute of Dental Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan; 2Department
of Orthodontics, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
A 28-year-old male presented to the Orthodontic clinic for correction of his anterior crossbite due to
mandibular prognathism as a result of pituitary adenoma with acromegaly. A radiographic
cephalometric analysis and clinical orthodontic examination were made. This article describes in
detail the methods of correcting the magnification of cephalometric linear measurements in sellar
dimensions (length, depth and width) from lateral and posteroanterior cephalograms. Cephalometric
findings revealed that the sella enlarged in all its dimensions with a deepening of the floor in this
acromegalic case. We discuss the radiographic diagnosis of an enlarged sella turcica in intrasellar
tumours and also emphasise the dentist’s important role in the initial diagnosis of pituitary adenoma
cases.
Dentomaxillofacial Radiology (2005) 34, 308–312. doi: 10.1259/dmfr/27388408
Keywords: sella; pituitary adenoma; acromegaly; cephalometric cephalograph
Introduction
The pituitary gland, also known as hypophysis, occupies the of his anterior crossbite due to mandibular prognathism.
hypophyseal fossa, which is the deep depression in the sella More than 8 months ago, enlargement of his lower jaw was
turcica. The hypophysis is divided both functionally and noticed by his family and friends. Acromegaly caused by
embryologically into an anterior and a posterior lobe, the pituitary adenoma with excess secretion of GH was then
adenohypophysis and neurohypophysis, respectively.1 detected by an endocrinologist, and the patient was
The most common cause of sellar enlargement is a primary referred to the neurosurgical department of the university
intrasellar pituitary tumour, which is usually a pituitary hospital for further surgical treatment where he underwent
adenoma.2 Pituitary adenomas are benign tumours located transsphenoidal microsurgical removal of the pituitary
in the sella turcica and usually associated with hypersecre- adenoma using the Hardy method (microsurgical trans-
tion of pituitary hormones. These hormones include growth sphenoidal hypophysectomy).4
hormone (GH), thyroid-stimulating hormone (TSH), adre- A routine set of orthodontic diagnostic records was
nocorticotropic hormone (ACTH), ovarian follicle-stimu- taken, consisting of upper and lower study models,
lating hormone (FSH), luteinizing hormone (LH) and intraoral and extraoral photographs, and radiographs
prolactin (PRL). The GH-secreting pituitary adenoma (panoramic radiograph, lateral cephalometric and poster-
leads to acromegaly, which is a highly disproportionate oanterior (PA) cephalometric radiographs) at the first visit
growth of the mandible and facial bones in post-pubertal to the Orthodontic clinic.
patients, mainly a result of reactivation of the subcondylar He had a concave facial appearance, which is the most
growth zones and also due to periosteal bone apposition.3 noticeable profile characteristic of acromegalic patient.5
The lateral profile indicated marked mandibular prognath-
ism with a prominent chin, enlarged lips, a bulbous nose
Case report and prominent supraorbital ridges. Oral examination and
study model analysis showed super Class III molar
A 28-year-old male presented to the Orthodontic clinic at and canine relationships and bilateral posterior crossbite
the Kaohsiung Medical University Hospital for correction and anterior crossbite with minimal crowding of the lower
arch. Cephalometric analysis revealed severe skeletal
Class III malocclusion (ANB ¼ 2 8.18; norm in adult
*Correspondence to: Dr Hong-Po Chang, Department of Orthodontics, Kaohsiung
male: 3.58 ^ 1.48) with slight maxillary retrusion
Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan;
E-mail: hopoch@kmu.edu.tw (SNA ¼ 808; norm: 84.38 ^ 2.58), severe mandibular
Received 21 October 2004; revised 25 February 2005; accepted 15 March 2005 prognathism (SNB ¼ 888; norm: 80.98 ^ 2.88) and veryEnlarged sella turcica
H-P Chang et al 309
severe anterior crossbite (negative incisal overjet of first to observe an abnormality in the sellar region of the
2 11.5 mm; norm: 3.3 mm ^ 1.4 mm). cranium. This initial diagnosis by an orthodontist and
Following combined orthodontic and orthognathic subsequent investigation and evaluation by an endocrinol-
surgical diagnosis, the orthodontic treatment of pre- ogist or neurosurgeon might sometimes be lifesaving to the
surgical decompensation for dentoalveolar compensation6 patient.
of proclined maxillary incisors and retroclined mandibular The AP dimension (length) is the longest AP diameter
incisors due to Class III skeletal relationship and the of the sella, while the depth is the longest perpendicular
orthognathic surgery with bilateral intraoral vertical ramus dimension between the diaphragmatic line and the sellar
osteotomy (IVRO)7 for mandibular setback were planned floor.10,15 The sellar floor may be delimited laterally on the
to correct the anterior crossbite and the prognathic PA cephalograph thus yielding the width of the sella.10,15
mandible, if the acromegalic condition was well controlled The sellar floor is recognized in the PA view of the skull
and the pituitary adenoma was not recurrent. The patient film in over 90% of cases and in 100% of cases using
was followed up for 1 year after the diagnosis in the tomography.15,16
university hospital. Endocrine studies revealed that the According to the “law of the similar triangles”
serum GH was not improved to normal level after the ratio of the corresponding sides is equal. Thus
transsphenoidal hypophysectomy and hormone control, the magnification factor for the lateral cephalogram
and orthodontic examinations also showed that a slightly can be calculated by the following formula:
continuing growth change of the occlusion and the magnification factor ¼ 150/(150 þ 15) ¼ 10/11 (anode-
craniofacial structure. At this time he has not undergone to-midsagittal ¼ 150 cm, midsagittal-to-film ¼ 15 cm).
orthognathic surgery. In this patient, the actual sella size was corrected from
Upon examination of the initial lateral and PA cephalo- measurements from the lateral cephalogram. The length
graphs, an abnormally sized sella turcica was detected was 14.3 mm £ 10/11 ¼ 13.0 mm and the depth was
(Figure 1). The anteroposterior dimension (length) was 13.4 mm £ 10/11 ¼ 12.2 mm.
13.0 mm and the depth was 12.2 mm, which were deduced The PA cephalogram presents different magnification.
from measurements from the lateral cephalogram. The The magnitude of enlargement in the PA cephalogram is a
width was 16.5 mm, which was deduced from measurement function of the distance between the anode and the
from the PA cephalogram. These values exceeded normal landmark as well as the distance between the anode and
figures for the dimensions of the sella in adult males of the
the cephalogram.17 This is the same geometric principle
20 – 29 years age group (norms in sella length: 10.82
mentioned above in the lateral cephalogram. In this case
mm ^ 1.47 mm, depth: 8.32 mm ^ 1.11 mm, and width:
the magnification factor for the PA cephalogram is the
13.28 mm ^ 1.87 mm).8 The methods of correcting the
distance between the anode and the transporionic axis
magnification of cephalometric linear measurements from
(150 cm) plus the corrected distance of the landmark (sella
lateral and PA cephalograms are detailed in the discussion
section of this report. The software9 used was written in the floor) to the transporionic axis measured from the lateral
“MATLAB 5.3” (Version 2.3; CAESAR Lab, NCKU, cephalogram (2.98 mm £ 10/11 ¼ 2.71 cm), divided by
Taiwan) and implemented on a 1.0 GHz Pentium III PC. the distance between the anode and the film (150 cm þ 15
cm ¼ 165 cm). The actual width of the sella was
17.8 mm £ [(150 þ 2.71)/165] ¼ 16.5 mm.
Discussion The radiographic differential diagnosis of an enlarged
sella turcica includes acromegaly, adenomas, craniophar-
The radiographic methods for detecting intrasellar tumours yngioma, empty sella syndrome, gigantism, intrasellar
include lateral, Towne’s, PA, and axial views/projections aneurysm, meningioma, Nelson syndrome, primary
of the skull.10 Computerized tomography (CT) scans have hypothyroidism, prolactinoma, and variant of nor-
also proved helpful to measure the size of the intrasellar mal.2,16,18,19 The most common cause of sellar enlargement
contents.11 The best method to determine the extent of is a primary intrasellar pituitary tumour, which is usually a
sellar enlargement and detect the presence of intrasellar pituitary adenoma.2 Patients with pituitary adenomas may
tumours is with magnetic resonance imaging (MRI).12 MRI present with symptoms of pituitary dysfunction and visual
is superior to CT in that it generates higher soft tissue abnormalities. Sometimes patients with an enlarged sella
contrast and has proved to be more sensitive for accurate are asymptomatic or present with only non-specific
delineation of sellar tumours and surrounding struc- headaches.2,19 In this patient, no symptoms were present.
tures.13,14 Although CT scan and MRI have replaced Enlargement of his lower jaw was noticed by his family,
plain films as the investigation of choice for suspected thus triggering the investigation that led to the detection of
pituitary abnormalities, it remains nevertheless imperative a pituitary adenoma by an endocrinologist. Ninety per cent
for the dental and medical practitioners to be aware of the of patients with any clinical signs of a pituitary adenoma
plain film appearance of sella turcica. have an enlarged sella.2 An enlargement of the sella may be
The dental profession can play an important role in the with or without bony destruction. In this case the sella
detection of skull lesions. Orthodontists, in particular, enlarged in all its dimensions with a deepening of the floor.
routinely take lateral cephalographs as part of the process The patient had undergone surgical treatment by trans-
of orthodontic diagnosis, treatment planning, and sphenoidal microsurgical removal of the anterior pituitary
assessment of therapeutic results. Hence they may be the adenoma4 8 months earlier. The surgical defect of the
Dentomaxillofacial RadiologyEnlarged sella turcica
310 H-P Chang et al
Figure 1 (a) Lateral and (c) posteroanterior (PA) cephalographs with corresponding diagrams (b and d) illustrate the method for measurement of sellar
dimensions. The surgical defect of the anterior sellar wall between four-to-five o’clock was discernible on the lateral cephalograph. The length
measurement represented the longest anteroposterior (AP) diameter of the sella, while the depth measurement was the longest perpendicular dimension
between the diaphragmatic line and the sellar floor (b). The width measurement was taken from the PA cephalograph. The diagram (d) indicated method of
width measurement for the “rounded edge” sellar floor.26 The actual dimensions (length, depth and width) of the sella were deduced from measurements
from the lateral and PA cephalograms. Correction of magnification of these linear measurements was detailed in the discussion
anterior sellar wall between four-to-five o’clock is subdivided into GH-secreting, ACTH-secreting, PRL-
discernible on the lateral cephalograph. secreting, FSH, LH secreting tumours or mixed type
The surgical specimen obtained from this patient via tumours.20 The diagnosis should be pathologically verified
transsphenoidal hypophysectomy was diagnosed by the by electron microscopy. Clinical symptoms are related to
pathological examination with light microscopy as baso- the type of hormone secreted. For instance, GH-secreting
philic pituitary adenoma. The pituitary adenomas can be adenomas cause elevated blood GH levels, acromegaly in
Dentomaxillofacial RadiologyEnlarged sella turcica
H-P Chang et al 311
adults and gigantism in children and ACTH-secreting 58% following surgery, reaching their final size by the
adenomas cause Cushing’s disease or Nelson’s syndrome. fourth month in most cases. The most significant reduction
Prolactinomas (PRL-secreting adenomas) are marked occurred during the first month. They concluded that the
clinically by amenorrhoea, galactorrhoea or loss of libido. post-operative MRI appearance of the sella stabilized by
Mixed GH- and ACTH-secreting adenoma generally 4 months when most of the post-surgical changes have
results in acromegaly, Cushing’s disease or Nelson’s resolved, and that the MRI was not useful for the follow-up
syndrome. Mixed GH- and PRL-secreting adenoma could of microadenomas (, 10 mm in diameter in the coronal
be correlated to clinical findings, such as acromegaly, images).
amenorrhoea, galactorrhoea or loss of libido. A dangerous sequel of pituitary adenoma is known as
Transsphenoidal selective hypophysectomy is the most pituitary apoplexy, which is a life-threatening episode
efficient and widely used method to treat acromegaly.21,22 caused by haemorrhagic infarction or necrosis of a
However, the acromegalic patients have a substantial risk pituitary tumour.12,24 Clinical manifestations include the
of recurrence of the pituitary adenoma, which causes sudden onset of headache, vomiting, signs of meningeal
growth changes in the facial skeleton even after removal of irritation, visual impairment, ophthalmoplegia, and
the pituitary adenoma and hormone control.21 The reported deterioration of consciousness level.24 This initial phase
long-term cure rates of transsphenoidal hypophysectomy can be life threatening and requires timely prompt
have been variable. Serri et al22 stated that the overall cure treatment. Almost all patients who experience pituitary
rate was 68%. Endocrine studies and orthodontic examin- apoplexy have sellar enlargement that is detectable on
ations should identify no relapse of the GH level or no lateral skull films.24,25 Therefore, early detection of sellar
significant change of the occlusion with the craniofacial abnormalities may benefit the patient and sometimes avert
structure in the acromegalic patient before the orthognathic a potentially life-threatening event.
surgery is performed for correction of the enlarged
mandible and anterior crossbite.
The pituitary gland occupies approximately 79% (on the
average) of the volume of the sella turcica15 and thus
considerable enlargement of the pituitary gland may not Acknowledgment
actually produce changes which can be seen on routine film The authors wish to thank Dr Yin-Ting Liu for assembling the
of the skull. Roddriguez et al,23 in a prospective study of clinical records examined in this study. This work was supported
pituitary adenomas, found that the contents of the sella by research grant from the National Science Council of Taiwan
turcica decreased in height by up to 81%, and on average (NSC 90-2314-B-037-087).
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