A rare epidermoid cyst occurring in an young female: a case report and literature review

Epidermoid cysts are very rare benign lesions of epithelial origin, slow growing extra-axial tumours and they accord for 1% of all intracranial tumours. They frequently occur at the cerebellopontine angle and parasellar regions insinuating brain structures. They are often associated with a high rate of residual tumor and recurrence. We present the case of a 18 year old patient who was admitted in the our clinic for secondary amenorrhea. The CT scan showed a large median mass with a mixed structure (calcareous and cystic) resembling a craniopharyngioma. Preoperatively the hormonal prole showed deciency of all anterior pituitary hormones. Transsphenoidal surgery was performed and the histopathological exam established the diagnosis of sellar epidermoid cyst with parasellar extension. Postoperatively the patient developed iatrogenic Cushing syndrome (due to large amounts of dexamethasone given) and diabetes insipidus. daily and 5 mg of prednisone. After the neurosurgical exam an MRI (magnetic resonance imaging) exam was performed which conrmed the intracranial mass in the sellar and suprasellar space of 23/18/23 mm with extension at the third ventricle. The transsphenoidal surgery was performed with the removal of the cerebral mass. The histopathological exam conrmed the diagnosis of epidermoid cyst. The high suspicion that had arisen after the CT scan was the main key of the diagnosis. The rst suspicion was of a craniopharyngioma and only after surgery and histopathological exam the diagnosis could be established. transsphenoidal approach of the suprasellar region without a complete resection due to the adherence to the optic chiasm and optic nerves. This is the rst case of a epidermoid cyst of the pituitary stalk with successful complete removal with a combined suprasellar and infrasellar approach. In the same meta-analysis the most common clinical presentations were: amenorrhea, diplopia or vision loss, The most common imaging ndings showed on the CT scan hypodense lesions and the presence of calcications (Table impairment. This case is unique in all literature due to the association of pituitary insuciency, diabetes insipidus and postoperative iatrogenic Cushing syndrome. Overall the evolution of the patient was favorable.


Abstract
Background Epidermoid cysts are very rare benign lesions of epithelial origin, slow growing extra-axial tumours and they accord for 1% of all intracranial tumours. They frequently occur at the cerebellopontine angle and parasellar regions insinuating brain structures. They are often associated with a high rate of residual tumor and recurrence.

Clinical Case
We present the case of a 18 year old patient who was admitted in the our clinic for secondary amenorrhea. The CT scan showed a large median mass with a mixed structure (calcareous and cystic) resembling a craniopharyngioma. Preoperatively the hormonal pro le showed de ciency of all anterior pituitary hormones. Transsphenoidal surgery was performed and the histopathological exam established the diagnosis of sellar epidermoid cyst with parasellar extension. Postoperatively the patient developed iatrogenic Cushing syndrome (due to large amounts of dexamethasone given) and diabetes insipidus.

Conclusion
Epidermoid cysts are challenging tumours because of the extension along the subarachnoid spaces around delicate neurovascular structures therefore they are di cult to be completely resected. The particularity of this case stands in the rare occurrence of this types of tumours and the fact that although in these patients with hypopituitarism diabetes insipidus is present primarily our patient developed postoperatively.

Background
Epidermoid cysts are lesions which develop from the neuroectodermal epithelial cells. They are benign lesions rarely undergoing malignant transformation (1). The intracranial location is uncommon, it can occur only in 1.5% of all epidermoid tumours and 0.3-1.8% of all intracranial tumours (2). In the majority of the cases the initial presentation is related to its local mass effect such as: hearing impairment, trigeminal neuralgia, facial palsy, diplopia, headaches, seizures etc (3). Surgical total resection remains the rst line therapy, however this may be not possible as the cyst wall can be adherent to neurovascular structures.
the most common complications after resection are: chemical meningitis, hydrocephalus, infectious meningitis and cranial nerve palsies (4). They can be found in the subarachnoid space, at the cerebellopontine angle and parasellar space (4). Only 3 epidermoid cysts involving the pituitary infundibulum have been reported in the literature ( 5,6,7). We report a case of a cerebral epidermoid cyst of the median line resected by a transsphenoidal approach. The patient, a young female, was admitted in our clinic for amenorrhea.

Case Presentation
A 18 year old female, non-smoker, presented for secondary amenorrhea (lack of menses for 1 year and 4 months). The patient had no family history and no relevant medical history, particularly no cranial trauma.
At the clinical exam the patient was overweight (BMI = 28,1 kg/m 2 ), normotensive neurologically intact excepting right visual eld impairment con rmed by the ophthalmological examination.
Laboratory evaluation revealed mild hyperlipemia and the hormonal pro le revealed the presence of panhypopituitarism -hypothyroidism, hypogonadism. The visual eld chart of the right eye showed temporal eld loss and bitemporal relative scotomas.
Pre and post contrast scans were performed including dynamic imaging through the pituitary fossa. A complex cystic lesion is seen in the suprasellar regiona mixed structure (calcarous and cystic) with a maximum diameter of 2.76/1.95/2.17 cm, resembling a cranyopharingioma (Fig. 1). The patient was discharged with the recommendations for neurosurgery and resection of the tumour, treatment with levothyroxine 50 micrograms daily and 5 mg of prednisone. After the neurosurgical exam an MRI (magnetic resonance imaging) exam was performed which con rmed the intracranial mass in the sellar and suprasellar space of 23/18/23 mm with extension at the third ventricle. The transsphenoidal surgery was performed with the removal of the cerebral mass.
The histopathological exam con rmed the diagnosis of epidermoid cyst. The high suspicion that had arisen after the CT scan was the main key of the diagnosis. The rst suspicion was of a craniopharyngioma and only after surgery and histopathological exam the diagnosis could be established.

Postoperative Evolution
Two weeks after surgery at follow-up the patient had polyuria and polydipsia (liquid intake of 6 l per day), therefore the therapy with desmopressin was initiated (60 micrograms twice per day). After two months the patient was readmitted in the endocrinology department for severe fatigue, weight gain (18 kg in 2 months), polyarthralgia, red stretch marks which appeared on the skin of the hands, armpits, thighs, inferior abdomen, hirsutism, palpitations. On clinical exam the patient was obese (BMI = 32,81 kg/m 2 ), moon face, normotensive, elevated heartbeat of 114 beats per minute. Laboratory test showed hyperlipemia and mild hepatic cytolysis. The hormonal con rmed the Cushing syndrome most probably iatrogenic due to large amount of dexametazone given postoperatively in the neurosurgical department and panhypopituitarism with adequate thyroid substitution for hypothyroidism with levothyroxine 50 micrograms daily, hypogonadism. (Table 2).  The cause of the amenorrhea was the secondary hypogonadism so estro-progestative treatment was initiated, the prednisone was stopped and the treatment with levothyroxine and desmopressin for the diabetes insipidus was continued. The optochiasmatic syndrome was partially resolved. Two years after surgery the cerebral IRM showed a tumour recurrence, a mass of 21/16/14 mm.

Discussion
Epidermoid cysts are congenital lesions resulting from sequestration of embryonic components of the epithelial tissue. 37,3% are located in the cerebellopontine angle (the most common location) followed by parasellar, middle fossa and the spinal channel. Long-therm survival is good, the rate of malignancy is very low.
One meta-analysis which included 508 reports identi ed only 11 pertinent cases (5). Only one case was located in the pituitary stalk underwent endoscopic endonasal transsphenoidal approach of the suprasellar region without a complete resection due to the adherence to the optic chiasm and optic nerves. This is the rst case of a epidermoid cyst of the pituitary stalk with successful complete removal with a combined suprasellar and infrasellar approach. In the same meta-analysis the most common clinical presentations were: amenorrhea, diplopia or vision loss, The most common imaging ndings showed on the CT scan hypodense lesions and the presence of calci cations (Table 3). Chronic endocrine disturbances can be the presenting complaints of a suprasellar epidermoid cyst. The suprasellar cistern is a cerebrospinal uid-lled space below the third ventricle with a oor formed by the dura of the diaphragm sellae.
Generally suprasellar epidermoid cysts have been excised by transfrontal craniotomics, but in the last years a less invasive transnasal endoscopic approach has been adopted. The rst craniotomy for a suprasellar epidermoid cyst was reported by Sadeh et al (8) when a subtotal resection was performed. A systematic review (Huo et al) showed that in the majority of cases reported in the literature of epidermoid cysts treated by combined endoscopic endonasal and endoscopic transphenoidal technique the short term outcomes included improvement vision, but in some cases visual loss persisted (Prasad et al), We, the authors, con rm that informed consent has been obtained from the patient for participation for the case report: A rare epidermoid cyst occuring in an young female: a case report and literature review. The presented case was approved by the ethics committee of the National Institute of Endocrinology C. I.

Consent for publication
We, the authors, con rm that informed consent has been obtained from the patient for publication for the case report: A rare epidermoid cyst occuring in an young female: a case report and literature review, and accompanying images.
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