DOI: 10.1148/radiol.2413032060
(Radiology 2006;241:936-938.)
© RSNA, 2006
Case 102: Pituitary Aplasia1
Luisa F. Cervantes, MD,
Nolan R. Altman, MD and
L. Santiago Medina, MD
1 From the Department of Radiology, Miami Children's Hospital, 3100 SW 62nd Ave, Miami, FL 33155. Received December 15, 2003; revision requested February 19, 2004; revision received May 25; accepted June 15; final version accepted October 20.
Correspondence: Address correspondence to L.F.C. (e-mail: lulu_cervantes{at}hotmail.com).
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HISTORY
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A full-term boy was born to a 33-year-old woman (gravida 3, para 2) after an uneventful pregnancy. The baby was delivered by means of cesarean section when labor failed to progress. At birth, the baby weighed 3685 g, was 50.8 cm long, and had an Apgar score of 8 at 1 minute and of 10 at 5 minutes. The baby's blood glucose level at 2 hours of age was 7 mg/dL (0.39 mmol/L). At that time, he was transferred to the regular nursery, and dextrose infusion was started. Twenty hours later, he was found to be lethargic and hypothermic. His blood glucose level was immediately measured and found to be 2 mg/dL (0.11 mmol/L). A physical examination was performed, and a micropenis and bilaterally descended testicles were noted. The patient was transferred to a tertiary pediatric medical center, and magnetic resonance (MR) imaging of the brain was performed.
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IMAGING FINDINGS
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Sagittal and coronal MR images obtained through the sella (Figure, parts a and b) showed the anterior pituitary gland was absent. The posterior pituitary gland, which is indicated by an area of high signal intensity, was not visible in either the sella or the hypothalamic region. The sella turcica was flattened and shallow. The optic chiasm was normal in size and morphology. The transverse MR image obtained through the suprasellar region (Figure, part c) showed that there was no pituitary stalk.
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Figure a: (a) Sagittal and (b) coronal T1-weighted MR images (repetition time msec/echo time msec, 500/12; section thickness, 3 mm) obtained through the sella show absence of the anterior pituitary gland. The absence of a high-signal-intensity area indicates that the posterior pituitary gland is not seen in either the sella or the hypothalamic region. The sella turcica (arrow) is flattened and shallow. The optic chiasm (arrowhead) is normal in size and morphology. (c) Transverse T1-weighted MR image (525/10; section thickness, 3 mm) obtained through the suprasellar region shows that there is no pituitary stalk, but there are normal optic nerves (arrowheads).
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Figure b: (a) Sagittal and (b) coronal T1-weighted MR images (repetition time msec/echo time msec, 500/12; section thickness, 3 mm) obtained through the sella show absence of the anterior pituitary gland. The absence of a high-signal-intensity area indicates that the posterior pituitary gland is not seen in either the sella or the hypothalamic region. The sella turcica (arrow) is flattened and shallow. The optic chiasm (arrowhead) is normal in size and morphology. (c) Transverse T1-weighted MR image (525/10; section thickness, 3 mm) obtained through the suprasellar region shows that there is no pituitary stalk, but there are normal optic nerves (arrowheads).
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Figure c: (a) Sagittal and (b) coronal T1-weighted MR images (repetition time msec/echo time msec, 500/12; section thickness, 3 mm) obtained through the sella show absence of the anterior pituitary gland. The absence of a high-signal-intensity area indicates that the posterior pituitary gland is not seen in either the sella or the hypothalamic region. The sella turcica (arrow) is flattened and shallow. The optic chiasm (arrowhead) is normal in size and morphology. (c) Transverse T1-weighted MR image (525/10; section thickness, 3 mm) obtained through the suprasellar region shows that there is no pituitary stalk, but there are normal optic nerves (arrowheads).
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DISCUSSION
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In a newborn, persistent neonatal hypoglycemia has multiple metabolic and endocrinologic etiologies. Metabolic etiologies are found in most instances of persistent neonatal hypoglycemia (1). However, the clinical finding of micropenis in our patient suggested hypopituitarism; thus, imaging studies were obtained and revealed aplasia of the pituitary gland. Congenital pituitary gland absence (aplasia) is a rare anomaly that involves absence of both the anterior and the posterior pituitary lobes and, in many cases, the pituitary stalk (2).
An endocrinologic cause of micropenis reflects a deficiency of testosterone, dehydrotestosterone, or growth hormone; these hormones are needed for normal penile growth to occur beyond 14 weeks of gestation. The major causes of micropenis include hypopituitarism (in 30% of cases), primary hypogonadism (in 25% of cases), and idiopathic undiagnosed causes (in 45% of cases) (1). The association of micropenis with early neonatal hypoglycemia should immediately raise the possibility of congenital hypopituitarism.
In patients with neonatal panhypopituitarism, severe symptoms of hypoglycemia may appear during the 1st hours of life. Symptoms include seizures, apnea, and cardiovascular collapse and arrest. The infants are of normal length and weight and are born at term or postterm. A physical examination may be unrevealing; however, some male infants have a microphallus, a poorly developed scrotum, and/or small undescended testes. Facial abnormalities—including cleft lip and palate, poorly developed nasal septum, and hypotelorism or hypertelorism—have been reported. Abnormalities of antidiuretic hormone secretion have also been described. Although the size of infants is normal at birth, growth retardation and delayed bone age may be found at 6–8 weeks of age (1).
Neonatal hypoglycemia associated with poorly functioning anterior pituitary gland may represent a series of separate syndromes with no structural brain anomalies or with defects such as craniofacial defects, absence of septum pellucidum, septo-optic dysplasia, arrhinencephaly, holoprosencephaly, and anencephaly (1). It is well known that anencephalic newborns lack an identifiable pituitary gland and have hypoplasia of the adrenal glands (3,4). Congenital absence of the pituitary gland without a major brain anomaly is a rare disorder. Most infants with this disorder die in early infancy, and the anomaly is diagnosed at autopsy.
The exact mechanism of hypoglycemia in panhypopituitarism remains unclear. Hypoglycemia is thought to result from a cortisol deficiency. Absence or severe atrophy of the fetal zone of the adrenal cortex is a consistent finding in patients with pituitary aplasia (3). This is thought to indicate an adrenocorticotropic hormone deficiency; histologic samples obtained in patients with this disorder have an appearance that is distinctly different from that of patients with primary adrenal hypoplasia, in whom fetal zone cells are preserved (3). Growth hormone deficiency may also contribute to the low blood glucose level. Hypopituitarism as a cause of hypoglycemia is self-limited, and older children may not need continued growth hormone therapy to maintain normal glucose concentration. Cortisol replacement for glucose control, however, may need to be continued even if growth hormone therapy is no longer essential. The normal size of the infant at birth has been explained by the presence of maternal growth hormone.
The characteristic imaging finding of pituitary aplasia is absence of an identifiable pituitary gland. In addition, the sella is small and flat, and it is sometimes covered by a layer of dura. The differential diagnosis includes severe hypoplasia of the pituitary gland. However, this was not the most likely diagnosis in this case, as there was no pituitary stalk or posterior pituitary gland. In addition, the sella was flattened, and this indicated that no pituitary tissue was formed. The differential diagnosis may also include empty sella, in which the pituitary gland is severely flattened. In patients with empty sella, the superior portion of the sella turcica appears empty but is actually filled with cerebrospinal fluid (5). The empty sella is presumed to result from a deficient diaphragma sellae with resultant extension of the cerebrospinal fluid into the sella, exposing it to cerebrospinal fluid pulsation and eventually resulting in enlargement of the sella turcica. Empty sella is an uncommon finding that is encountered in children (6). Most frequently, the empty sella is an incidental finding of little or no clinical importance. Patients with empty sella do not have related endocrine abnormalities because the pituitary function is normal. In patients with empty sella, the sella is normal or enlarged.
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FOOTNOTES
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| Part one of this case appeared 4 months previously and may contain larger images.
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References
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- Kalhan SC, Parimi PS. Metabolic and endocrine disorders. In: Fanaroff AA, Martin RJ, eds. Neonatal-perinatal medicine: diseases of the fetus and infants. 7th ed. St Louis, Mo: Mosby, 2002; 1355–1367.
- Barkovich AJ. Congenital malformations of the brain and skull. In: Barkovich AJ. Pediatric neuroimaging. 3rd ed. Philadelphia, Pa: Lippincott Williams & Wilkins, 2000; 351–352.
- Sadeghi-Nejad A, Senior B. A familial syndrome of isolated "aplasia" of the anterior pituitary: diagnostic studies and treatment in the neonatal period. J Pediatr 1974;84:79–84.[CrossRef][Medline]
- Blizzard RM, Alberts M, Moines D. Hypopituitarism, hypoadrenalism and hypogonadism in the newborn infant. J Pediatr 1956;48:782–792.[CrossRef][Medline]
- Kucharczyk W, Montanera WJ, Becker LE. The sella turcica and the parasellar region. In: Atlas S, ed. Magnetic resonance imaging of the brain and spine. 2nd ed. Philadelphia, Pa: Lippincott-Raven, 1996; 880–883.
- Zucchini S, Ambrosetto P, Carla G, Tani G, Franzoni E, Cacciari E. Primary empty sella: differences and similarities between children and adults. Acta Paediatr 1995;84:1382–1385.[Medline]
Congratulations to the 77 individuals and five resident groups that submitted the most likely diagnosis (pituitary aplasia) for Diagnosis Please, Case 102. The names and locations of the individuals and resident groups, as submitted, are as follows:
Individual responses
- Gholamali Afshang, MD, Tinley Park, Ill
- Dr Erhan Akpinar, Ankara, Turkey
- Canan Altay, MD, Balcova, Izmir, Turkey
- Ken Baliga, Rockford, Ill
- Michael Lewis Black, MD, Irvine, Calif
- Eric L. Bressler, MD, Minnetonka, Minn
- Daniel F. Broderick, MD, Jacksonville, Fla
- Douglas C. Brown, MD, Virginia Beach, Va
- Carlos Capiel, Jr, MD, Mar del Plata, Buenos Aires, Argentina
- Kam Wai Chan, Hong Kong, Hong Kong
- Natesan Chidambaranathan, MD, Chennai, India
- Royce A. Chrys, MD, Oakland, Calif
- Haris Chrysikopoulos, MD, Kerkyra, Greece
- Yves-Sebastien Cordoliani, MD, Paris, France
- Marc G. de Baets, MD, Lugano, Switzerland
- J. F. K. de Villiers, Gisborne, New Zealand
- Jon James De Witte, Bishop, Ga
- Seena Dehkharghani, MD, Phoenix, Ariz
- Seyed Emamian, MD, PhD, Rockville, Md
- Shella Farooki, MD, Dublin, Ohio
- Dr James FitzGerald, Milsons Point, New South Wales, Australia
- Akira Fujikawa, Tokyo, Japan
- Karthik Ganesan, Mumbai, India
- Douglas Joseph Gardner, MD, Windsor, Ontario, Canada
- Moshe Goldfeld, Nahariya, Israel
- Mark G. Goldshein, MD, Andover, Mass
- Dan G. Gridley, MD, Phoenix, Ariz
- Ferris M. Hall, MD, Boston, Mass
- Alberto Iaia, MD, Wilmington, Del
- Mehmet Kocak, MD, Milwaukee, Wis
- Kaori Koga, Oakleigh, Australia
- Kavitha Kothur, Hyderabad, Andhra Pradesh, India
- Mario Laguna, West Allis, Wis
- Dr Martin Lecompte, Ottawa, Ontario, Canada
- John Lai Yin Leung, MBBS, Chai Wan, Hong Kong
- Marina Lucchesi, Junin, Buenos Aires, Argentina
- Naganathan B. S. Mani, MD, Nassau, Bahamas
- Michael B. Martin, MD, Austin, Tex
- Fernando Mas-Estelles, Valencia, Spain
- Waldir Heringer Maymone, MD, Rio de Janeiro, Brazil
- Nikolaos Michailidis, MD, Thessaloniki, Greece
- Manabu Minami, MD, Tsukuba, Ibaraki, Japan
- Jose Mondello, MD, Buenos Aires, Argentina
- Albert Nizzero, MD, Sudbury, Ontario, Canada
- Laura Oleaga, MD, Bilbao, Spain
- Sanford M. Ornstein, MD, Phoenix, Ariz
- Ann Burleson Owen, MD, Murfreesboro, Tenn
- Rajeev Padmanabhan, MBBS, Newcastle upon Tyne, United Kingdom
- Harish Panicker, MD, Hermitage, Pa
- Narendrakumar P. Patel, MD, Newburgh, NY
- Prakash N. Patel, MD, New City, NY
- Yeliz Pekcevik, Izmir, Turkey
- Henry F. W. Pribram, MD, Laguna Beach, Calif
- Prashant Raghavan, MD, Charlottesville, Va
- Marcio Bustamante Sa Rodrigues, MD, Rio de Janeiro, Brazil
- Tsutomu Sakamoto, MD, Tokyo, Japan
- Hatice Tuba Sanal, MD, Ankara, Turkey
- Steven Schepers, MD, Herent, Belgium
- Anthony J. Scuderi, Johnstown, Pa
- Matt Shapiro, MD, Charlottesville, Va
- Grady Shue, Jr, MD, Hickory, NC
- Ken Simmons, Sydney, Australia
- David F. Sobel, MD, La Jolla, Calif
- James D. Sprinkle, Jr, MD, Spotsylvania, Va
- Vinod Sukumaran II, MD, Trivandrum, India
- Venkateswar Rao Surabhi, MBBS, Herndon, Va
- Douglas L. Teich, MD, Brookline, Mass
- Kazuma Terauchi, Fujieda, Shizuoka, Japan
- Dr Özgür Tosun, Bilkent, Ankara, Turkey
- Shigeaki Umeoka, MD, Wakayama, Japan
- Eleni Vafeiadou, Thessaloniki, Greece
- Joan C. Vilanova, MD, Girona, Spain
- Christopher P. Vittore, MD, Rockford, Ill
- Nikolaos Vougiouklis, Kalamaria, Greece
- Robert Charles Weissmann, MD, Birmingham, Ala
- Steven Thomas Welch, MD, Kansas City, Mo
- Edward Williams, Isle of Man, United Kingdom
Resident group response
- Hospital Italiano Córdoba Radiology Residents, Córdoba, Argentina
- Kyoto City Hospital Radiology Residents, Kyoto, Japan
- Maine Medical Center Radiology Residents, Portland, Me
- Trakya University School of Medicine Radiology Residents, Edirne, Turkey
- University of Pennsylvania Radiology Residents, Philadelphia, Pa
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HISTORY
IMAGING FINDINGS
