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Journal of Cancer Research and Therapeutics, Vol. 5, No. 4, October-December, 2009, pp. 309-311 Case Report Chordoma with increased prolactin levels (pseudoprolactinoma) mimicking pituitary adenoma: A case report with review of the literature Kumar Pavan, Kumar Piyush, Singh Shalini, Kumari Niraj, Datta NR Department of Radiotherapy, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow Code Number: cr09074 PMID: 20160370 DOI: 10.4103/0973-1482.59912 Abstract The article deals with a rare case of chordoma with increased prolactin levels. It could often result in a diagnostic dilemma and problems in differentiating it from a pituitary adenoma.Keywords: Chordoma, pituitary adenoma, pseudoprolactinoma Introduction Chordomas are rare neoplasms of the axial skeleton arising from remnants of primitive notochord. The tumor typically originates either in sacrum or clivus and usually presents with headache, visual disturbances, nasal stuffiness, or cranial nerve defects. Increased serum prolactin levels are diagnostic of prolactin secreting pituitary adenoma and are rarely seen with chordomas. Hyperprolactinemia in these cases could result in a diagnostic dilemma. To the best of our knowledge, only two such cases of chordoma mimicking a pituitary tumor have been reported in the literature so far. [1],[2] Case Report A 60-year-old, postmenopausal lady presented to the department of neurosurgery with the complaints of headache, grand mal-seizures, diplopia, and progressive vision loss in both eyes for 2 months. Ophthalmic examination revealed visual acuity of 6/60 and 6/36 in the right and left eye respectively with bitemporal field defects along with bilateral primary optic atrophy. There were no other neurological deficits. Computed tomography (CT) showed a contrast-enhancing sellar and suprasellar mass with right parasellar extension and few specks of calcification. The sella was enlarged and showed destruction of the floor. On magnetic resonance imaging (MRI), T1- and T2-weighted images revealed a similar lesion with mass effect on optic chiasm [Figure - 1]a, b, and c. Pituitary gland was not seen separately. The prepontine cistern and clivus fat signals were maintained [Figure - 1]c. On endocrinal work-up, serum TSH and free thyroxin levels were 3.82 mIU/ml (normal 0.270-4.20 mIU/ml) and 9.55 pmol/l (normal 12.00-22.00 pmol/l) respectively. Serum prolactin levels were markedly elevated to 1982.0 mIU/ml (normal for females: 72-511 mIU/ml). The patient was started on intravenous dexamethasone (4 mg every 6 h), phenytoin (100 mg every 8 h), and thyroxine (0.1 mg once daily) prior to surgery. She underwent right pterional craniotomy and decompression of the lesion. Peroperatively, the tumor was grey coloured, firm, and relatively avascular with variable consistency. Histopathology [Figure - 2]a of the resected specimen showed tumor disposed in cords and groups embedded in an extensive myxoid background. On immunohistochemistry, tumor cells were positive for cytokeratin, epithelial membrane antigen, and S 100 [Figure - 2]b. Based on these findings, the diagnosis of a sellar suprasellar chordoma with an increased prolactin level ("pseudoprolactinoma") was established. Postoperatively, the patient showed gradual improvement in all the symptoms and was referred for adjuvant radiotherapy (RT). She was planned for RT to the local site by two parallel opposing lateral fields and a dose of 54 Gy in 30 fractions over a period of 6 weeks. At the follow-up of 12 months, her prolactin level was normalized to 379 mIU/ml. She was maintained on Tab. phenytoin, Tab. prednisolone (7.5 mg daily), and Tab. thyroxine (100 µg daily) and was on regular follow-up. After 2 years post-RT, she presented with complains of recurrent vomiting, headache, and deterioration of vision for last 15 days. A MRI scan showed recurrence of tumor with right parasellar extension, compressing the optic chiasm and invading cavernous sinus. She had a right MPVP shunt placement as she had features of raised intracranial tension and was planned for surgical decompression; however, her general condition deteriorated and she succumbed to the disease 3 years after the initial diagnosis. Discussion Chordomas are tumors of axial skeleton arising from primitive notochord remnants and constitute approximately 2-4% of all primary bone tumors. [3] About 50% arise in the sacrococcygeal area and 35% arise intracranially (where they typically involve the clivus). The remaining 15% occur in the midline along the path of the notochord, primarily involving cervical vertebrae. [4] A male predominance is reported with a sex ratio of 2:1 to 3:1. [5] Chordomas are slow-growing, locally invasive tumors which invade adjacent bone and soft tissues. The lethality of these tumors rests on their critical location, aggressive local behavior, and extremely high local recurrence rate. [6] On CT and MRI, the chordomas of the skull base are usually found to have a lobulated, "honeycomb" appearance, that may extend posteriorly to prepontine cistern, Circle of Willis, cavernous sinuses, brain stem, and cause bone erosion. [7] Sellar and suprasellar chordomas may mimic pituitary adenoma, but are usually differentiated by the presence of calcification and/or bony destruction in the former condition and hormonal hypersecretion in the latter condition. However, a chordoma presenting with increased prolactin levels ("pseudoprolactinoma"), as in this case, is very rare. "Pseudoprolactinoma" obstructs the flow of dopamine to the pituitary gland through the hypothalamic pituitary axis, and this loss of dopaminergic inhibition on the pituitary lactotrophs, the "stalk section effect," causes a rise in serum prolactin levels. However, prolactin levels are usually less than 2 U/l (100 µg/l). Treatment with dopamine agonist reduces prolactin levels but does not result in tumor shrinkage. Therefore, surgical decompression is usually the treatment modality of choice. [2],[8] On the other hand, true prolactinomas are usually characterized by prolactin levels of more than 2 U/l (100 µg/l) and usually respond to the treatment by dopamine agonists like bromocriptine, with tumor shrinkage occurring in about two-thirds of the patients. [2],[8] Moreover, there may be clinical manifestations of amenorrhea - galactorrhea syndrome, which is rare in pseudoprolactinomas. A preoperative differentiation between prolactinomas and pseudoprolactinomas is useful to decide between surgical and medical treatment. However, this is often not possible. The retrospective study of 44 cases by Smith et al. showed that there was no significant correlation of prolactin level and the degree of pituitary stalk compression, stalk deviation, or tumor size as seen on MRI. The differentiation between prolactinomas and pseudoprolactinomas could therefore be difficult on MRI. [2] In the present case, significant calcification and bony destruction were not evident on preoperative imaging studies. Moreover, due to extensive disease, normal pituitary gland could not be distinguished from the rest of the lesion. Further, she was postmenopausal and had amenorrhea; therefore, clinically, the differentiation between the prolactinoma and pseudoprolactinomas was not possible. Pituitary adenomas may rarely present with posterior extension or destructive invasion of the clivus leading to difficulties in differentiating from chordoma. [9] Thus, in the presence of significant hyperprolactinemia (that was much higher than may be seen in the "stalk section effect"), differentiation between a prolactinoma and pseudoprolactinoma was just not possible preoperatively in our case. Total removal of chordoma is a theoretical goal, which is seldom achieved since these lesions have a distinct tendency to invade the surrounding bone. Adjuvant therapy in the form of postoperative RT has therefore been mostly advocated. This could be delivered through stereotactic radiosurgery/radiotherapy in centers where such facilities are available. [10] Conclusion A rare case of chordoma with increased prolactin levels (pseudoprolactinoma) is reported. The entity presents a preoperative diagnostic dilemma until a surgical intervention is carried out. References
Copyright 2009 - Journal of Cancer Research and Therapeutics The following images related to this document are available:Photo images[cr09074f1.jpg] [cr09074f2.jpg] |
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