DOI: 10.1148/radiol.2342030645
(Radiology 2005;234:411-414.)
© RSNA, 2005
Case 79: Pituitary Duplication1
Christopher P. Vittore, MD,
Robert A. Murray, MD and
Laura S. Martin, MD
1 From the Departments of Radiology (C.P.V., R.A.M.) and Pediatric Genetics (L.S.M.), University of Illinois College of Medicine, Rockford Memorial Hospital, 2400 N Rockton Ave, Rockford, IL 61103. Received April 17, 2003; revision requested July 2; revision received July 13; accepted August 22. Address correspondence to C.P.V.
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HISTORY
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A 5-month-old full-term female infant was referred for imaging. The patient had a nasal pit, cleft palate, and esotropia. A bifid nasal tip and uvula were present. There was no known exposure to teratogens, drugs, or infectious agents. Apgar scores were 8 and 9 at 1 and 5 minutes, respectively.
Serum electrolyte, calcium, glucose, creatinine, blood urea nitrogen, free thyroxine, thyroid stimulating hormone, and cortisol levels were all normal. Magnetic resonance (MR) imaging of the brain was performed.
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IMAGING FINDINGS
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MR imaging of the brain shows the sella is shallow, and no pituitary stalk or gland is visible at the midline (Fig 1). A thickened "bar" of soft tissue runs along the floor of the third ventricle in the distribution of the hypothalamus from the mesencephalon to the posterior margin of the optic chiasm. The tissue demonstrates homogeneous signal intensity that is isointense with gray matter on T1- and T2-weighted images (Fig 2). Coronal thin-section images show duplicated pituitary infundibula extending below the optic chiasm to two small paramidline pituitary glands (Fig 3). Additional anomalies include lateralization of the colliculi at the quadrigeminal plate, with a capacious sylvian acqueduct (Fig 4). The basilar artery is duplicated, with the vertebral arteries parallel to each other in front of the brain stem (Fig 5) before they diverge to form the respective posterior cerebral arteries. The massa intermedia is absent (Fig 6).
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Figure 1. Midline sagittal unenhanced T1-weighted MR image (repetition time msec/echo time msec, 500/8) shows elongated mass-like thickening (single solid arrow) along the floor of the third ventricle. No pituitary gland or definite stalk is visible. Sella is shallow. Quadrigeminal plate appears thinned (open arrow). Cleft palate defect is evident (double arrows). The patient required general anesthesia for the examination, and the required airway intubation results in mild pharyngeal distortion. Note medial margin of the thalamus (*).
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Figure 3a. Sequential posteroanterior thin-section coronal three-dimensional spoiled gradient-echo MR images (33.3/6; flip angle, 35°). (a) Two paramidline pituitary infudibula (arrows) extend below the optic chiasm. (b) Infundibula continue to two small pituitary glands (arrows).
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Figure 3b. Sequential posteroanterior thin-section coronal three-dimensional spoiled gradient-echo MR images (33.3/6; flip angle, 35°). (a) Two paramidline pituitary infudibula (arrows) extend below the optic chiasm. (b) Infundibula continue to two small pituitary glands (arrows).
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Figure 4. Transverse unenhanced T1-weighted MR image (600/14). The thinned appearance of the quadrigeminal plate (arrow) at the midline results from lateralization of the colliculi. Sylvian acqueduct is widened (*).
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Figure 5a. (a) Coronal T2-weighted MR image (3200/90) shows nonunion of the vertebral arteries (arrows) anterior to the pons. (b) Transverse proton-density-weighted MR image (4450/12) shows duplicated basilar arteries (arrows). The vessels remained separate distally before becoming respective posterior cerebral arteries.
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Figure 5b. (a) Coronal T2-weighted MR image (3200/90) shows nonunion of the vertebral arteries (arrows) anterior to the pons. (b) Transverse proton-density-weighted MR image (4450/12) shows duplicated basilar arteries (arrows). The vessels remained separate distally before becoming respective posterior cerebral arteries.
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DISCUSSION
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Duplication of the pituitary gland is a rare occurrence; to our knowledge, only 17 cases have been reported (1–5). All the cases have shown accompanying abnormalities of the face or brain. Midline craniofacial abnormalities are commonly associated with duplication of the pituitary gland and include hypertelorism, cleft palate, mouth and tongue dysmorphism, persistence of the craniopharyngeal canal, midline clival defects, choanal atresia, and ectopic adenohypophyseal or hamartomatous pharyngeal masses. Some authors (6,7) have included pituitary duplication in the spectrum of median cleft face syndrome (frontonasal dysplasia).
Visualization of the duplicated infundibulum and pituitary gland is diagnostic, but many other abnormalities have been associated with this disorder (1). A characteristic midline, elongated mass, or thickening at the floor of the third ventricle is the most common intracranial abnormality associated with pituitary duplication. Histologic examination of this bar of tissue shows "small, tightly packed nerve cells interspersed by glial cells" (8) and is consistent with arrested cells that would normally migrate laterally to form hypothalamic nuclei (1). In five of the prior cases, cerebellar hypoplasia was reported (1,3); in this case, vermian hypoplasia was present. Although thalamic fusion was described in two cases (1), the massa intermedia is absent in the case we present. The corpus callosum, anterior commisure, septum pellucidum, anterior falx, and olfactory nerves may also be absent. Migrational abnormalities, hydrocephalus, microcephaly, vascular anomalies, and midline spinal defects have also been described (1).
Pituitary development is often presented as an ectodermal pouch (Rathke pouch) growing upward from the stomodeum, meeting and fusing with a neuroectodermal downgrowth from the diencephalon. These form the adenohypophysis and neurohypophysis, respectively (9). It would seem that interruption of this process would produce two separate hypophyseal portions or absence of part or all of the pituitary gland rather than two separate compositionally complete pituitaries. However, Gilbert (10) showed in 1935 that the pituitary originates from a single structure, a persistent point of adherence between the surface ectoderm and neuroectoderm, which exists prior to the formation of the ectodermal pouch. Division of this single primitive structure provides a more logical mechanism for duplication. Given the early embryonic relationships in this area, it is likely that pituitary duplication occurs as a result of duplication at the rostral end of the prochordal plate or notochord (11). Neuroectodermal disjunction may alternatively occur as a primary event, which could explain the lack of major associated malformations in some cases (5).
The differential diagnosis of a homogeneous mass at the floor of the third ventricle includes hypothalamic hamartoma and hypothalamic glioma. Hypothalamic hamartomas are found between the infundibular stalk and mamillary bodies, although they can extend into the interpeduncular cistern. They are round or oval-shaped, as opposed to the bar configuration seen in this case, and clinical associations include precocious puberty and gelastic seizures (12). Gliomas that arise from the hypothalamus often extend into the optic chiasm, but this structure is normal in this patient. Although gliomas typically show mild to moderate enhancement, contrast media were not administered in this case. Contrast media-enhanced images may be helpful in making the key findings more apparent, since the pituitary glands and stalks show enhancement.
Nonvisualization of the pituitary gland or stalk on the midline sagital MR image raises concern for pituitary absence or hypoplasia. In these situations, the sella is also small and flattened. However, pituitary aplasia is almost always fatal at birth. An absent or transected pituitary stalk is frequently associated with an ectopic neurohypophysis, which appears as a bright spot at the hypothalamus on T1-weighted images. These images show neither an ectopic nor an orthotopic bright spot. The absence of this finding at the posterior pituitary glands may be a result of their diminished sizes. The patient did not have diabetes insipidus.
In patients with pituitary duplication, coronal MR imaging demonstrates two pituitary stalks, and these should be sought when the associated characteristic bar of tissue is identified along the floor of the third ventricle. Of the cases reported in the literature, we believe this report is the first in which pituitary duplication is associated with an absent massa intermedia and complete basilar artery duplication.
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REFERENCES
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- Kollias SS, Ball WS, Prenger EC. Review of the embryologic development of the pituitary gland and report of a case of hypophyseal duplication detected by MRI. Neuroradiology 1995; 37:3-12.[CrossRef][Medline]
- Shah S, Pereira JK, Becker CJ, Roubal SE. Case report: duplication of pituitary gland. J Comput Assist Tomogr 1997; 21:459-461.[CrossRef][Medline]
- Hamon-Kérautret M, Soto Ares G, Demondion X, Rouland V, Francke JP, Pruvo JP. Duplication of the pituitary gland in a newborn with median cleft face syndrome and nasal teratoma. Pediatr Radiol 1998; 28:290-292.[CrossRef][Medline]
- Vandenhaute B, Leteurtre E, Lecomte-Houcke M, et al. Epignathus teratoma: report of three cases with a review of the literature. Cleft Palate Craniofac J 2000; 37:83-91.[CrossRef][Medline]
- Burke M, Zinkovsky S, Abrantes MA, Riley W. Duplication of the hypophysis. Pediatr Neurosurg 2000; 33:95-99.[CrossRef][Medline]
- Hori A. A brain with two hypophyses in median cleft face syndrome. Acta Neuropathol 1983; 59:150-154.[CrossRef][Medline]
- Ryals BD, Brown DC, Levin SW. Duplication of the pituitary gland as shown by MR. AJNR Am J Neuroradiol 1993; 14:137-139.[Abstract]
- Tagliavini F, Pilleri G. Mammillo-hypophyseal duplication (diplo-mammillo-hypophysis). Acta Neuropathol 1986; 69:38-44.[CrossRef][Medline]
- Moore KL, Persaud TV. The nervous system. In: Moore KL, Persaud TV, eds. The developing human: clinically oriented embryology. 6th ed. Philadelphia, Pa: Saunders, 1998; 470-473.
- Gilbert MS. Some factors influencing the early development of the mammalian hypophysis. Anat Rec 1935; 62:337-359.[CrossRef]
- Morton WR. Duplication of the pituitary and stomatodaeal structures in a 38-week male infant. Arch Dis Child 1957; 32:135-141.
- Barkovich AJ. Intracranial, orbital, and neck tumors of childhood. In: Barkovich AJ, eds. Pediatric neuroimaging. 3rd ed. Philadelphia, Pa: Lippincott Williams & Williams, 2000; 518.
Congratulations to the 57 individuals who submitted the most likely diagnosis (pituitary duplication) for Diagnosis Please, Case 79. Credit was given only if duplication of the pituitary gland was specifically mentioned. The names and locations of the individuals, as submitted, are as follows:
- Gholamali Afshang, MD, Tinley Park, Ill
- Brian Bigoni, Del Mar, Calif
- Eric L. Bressler, MD, Minnetonka, Minn
- Douglas C. Brown, MD, Virginia Beach, Va
- Luisa Fernanda Cervantes, Miami, Fla
- Marcos N. Chagas, MD, Brasilia, Brazil
- Dr N. Chidambaranathan, Chennai, India
- Haris Chrysikopoulos, MD, Kerkyra, Greece
- Sebastian Costantino, MD, Mar del Plata, Argentina
- Manuel de Juan Delago, MD, PhD, Barcelona, Spain
- Jose Luiz F. De Mendonca, MD, Brasilia, Brazil
- J. F. K. de Villiers, Gisborne, New Zealand
- Mustafa Kemal Demir, MD, Istanbul, Turkey
- James Easterbrook, MD, Greenville, NC
- Monica Epelman, Pittsburgh, Pa
- Akira Fujikawa, Tokyo, Japan
- Thomas C. Gallagher, DO, Yardley, Pa
- Cristine Norwig Galvão, Barretos, Brazil
- Gilles Genin, Annecy, France
- Alvaro Gomez Naar, Salta, Argentina
- Dan Gridley, Goodyear, Ariz
- John D. Grizzard, MD, Midlothian, Va
- Kathleen R. Groom, Fort Campbell, Ky
- Andreas Harzheim, MD, Cologne, Germany
- Steven A. Klein, MD, Shrewsbury, Mass
- Dr Wiebke Kurre, Frankfurt, Germany
- Iñigo Lecumberri, Bilbao, Spain
- Andy Leist, MD, Barcelona, Spain
- Richard A. Levy, MD, Saginaw, Mich
- John T. Lim, MD, Newport Coast, Calif
- N. B. S. Mani, MD, Nassau, Bahamas
- Manabu Minami, MD, Ibaraki, Japan
- Eduardo Mondello, MD, Buenos Aires, Argentina
- Suresh K. Mukherji, MD, Ann Arbor, Mich
- Marcos Nogueira, Brasilia, Brazil
- David Ozretic, Cakovec, Croatia
- Narendrakumar P. Patel, MD, Newburg, NY
- Maria Olga Patino, MD, Houston, Tex
- Dr Pieter M. Pretorius, Oxford, United Kingdom
- Matt Rheinboldt, Nashville, Tenn
- Randall E. Rhodes, MD, Belvidere, Ill
- Guis Saint-Martin, Rio de Janeiro, Brazil
- Mustafa Secil, MD, Izmir, Turkey
- Taro Shimono, MD, Osaka, Japan
- Scott D. Steenburg, MD, Mount Pleasant, SC
- Kouichi Sugiyama, Hamamatsu, Japan
- Norio Takahashi, MD, Fukui, Japan
- Douglas L. Teich, MD, Brookline, Mass
- Eugene Tong, MD, Austin, Tex
- Sanal H. Tuba, MD, Diyarbak
r, Turkey
- Akira Uchino, Saga, Japan
- Hiroyuki Ueda, Kyoto, Japan
- Elida Vazquez, MD, Seattle, Wash
- Nikolaos Vougiouklis, Thessaloniki, Greece
- Ed Weinberger, MD, Seattle, Wash
- Joe Yut, Olathe, Kan
- Yu Zhang, Nagoya, Japan
TOP
HISTORY
IMAGING FINDINGS
