Section 3 -

Case Reports: Case 2 George Kontogeorgos Department of Pathology, G. Gennimatas General Hospital, Athens , Hellas

A 32-year-old woman was presented with a 10-day history of fever (38.0o C), without rigors, frontal-temporal headaches, weakness, nausea and vomiting. Her past medical history included a 6 months history of diabetes insipidus and secondary amenorrhea without galactorrhea. Two months before her admission to our Department, she underwent a surgical drilling of the right mastoidea, due to right mastoiditis. Pathological examination revealed non-specific inflammatory granulation tissue. Endocrine investigation showed elevated serum PRL levels at 1880 mU/l (normal: < 360), a secondary adrenal and gonadal failure and a normal thyroid function. Case 2 - Figure 1 - Saggital contrast-enhanced magnetic resonance image revealing a large intrasellar mass of intense and heterogeneous enhancement with suprasellar extension and thickening of the pituitary stalk. Case 2 - Figure 2 - Granulomas composed of epithelioid histiocytes and multinucleated giant cells admixed with lymphocytes (H&E 10X). Case 2 - Figure 3 - Higher magnification of epithelioid granuloma (H&E 20X). Case 2 - Figure 4 - Epithelioid granuloma. Neutrophil accumulation with microabcess formation is noted (H&E 20X). Case 2 - Figure 5 - Typical caseous necrosis (H&E 10X). Case 2 - Figure 6 - Higher magnification of caseous necrosis (H&E 20X). Case 2 - Figure 7 - CD-68 immunoreactivity of epithelioid and multinuclear giant cells (ABC 10X). Case 2 - Figure 8 - Remnants of adenohypophysial nest adjacent to a multinuclear giant. Note somatotroph cells immunoreactive for GH (ABC 20X). Case 2 - Figure 9 - Remnants of adenohypophysial nest adjacent to a multinuclear giant with lactotroph cells immunoreactive for PRL (ABC 20X). Case 2 - Figure 10 - A few corticotroph cells immunoreactive for ACTH within epithelioid granuloma (ABC 20X). Case 2 - Figure 11 - Adenohypophysial cells adjacent to multinuclear giants immunoreactive for -SU (ABC 20X). Case 2 - Figure 12 - PCR products of the first line round (lanes 2 to 4) and the nested (lanes 6 to 8) amplification of mycobacterial 16S rDNA. Lanes 1, 5 and 9: molecular weight marker VI (Boehringer Mannheim, Mannheim, Germany); lanes 2 to 4: first round amplification, 2: patient's specimen, 3: positive control, 4: negative control; lanes 6 to 8: nested amplification, 6: patient specimen, 7: positive control, 8: negative control. Sequencing was performed from the nested amplification product (lane 6). All blood, sputum and urine cultures were negative for common bacteria, mycobacteria and fungi. A lumbar puncture of cerebrospinal fluid (CSF) was suggestive of aseptic meningitis. The Ziehl-Nielsen (Z-N) stain CSF fluid yielded negative result for acid-fast bacilli, while the tuberculin skin test was negative. In addition, a polymerase chain reaction (PCR) analysis for M. tuberculosis DNA in CSF, gastric juice and urine gave also negative results. Cranial MRI scan revealed a contrast enhancing intrasellar mass approx. 2 cm of heterogeneous appearance with suprasellar extension and thickening of the pituitary stalk. The pituitary mass was removed by a transsphenoidal approach. Histological examination demonstrated destruction of the adenohypophysis by epithelioid granulomas with partial caseous necrosis and microabscess formation, suggestive of a mycobacterial related infection. Z-N stain failed to reveal acid-fast bacilli. As histopathological diagnosis was strongly suggestive of a mycobacterium-related infection, a PCR assay performed in paraffin-embedded was performed that was positive for mycobacterial DNA. According to the individual 16S sequence, it was identified as Mycobacterium malmoense, an atypical nontuberculous mycobacterium (NTM). The patient was placed on appropriate antimycobacterial treatment and hormonal replacement therapy. Six months later a new pituitary MRI scan showed that the pituitary lesion was completely removed. The patient i­s doing well, free of any sign and symptoms of the disease after a 9 years follow-up. To our knowledge, this is the first case of an isolated pituitary granuloma caused by an NTM infection in a non-immunosuppressed patient diagnosed by PCR technique. Discussion Pituitary granulomas represent rare lesions including syphilis, tuberculosis, sarcoidosis, Langerhans' cell histiocytosis, Wegener's granulomatosis and giant cell granulomatous hypophysitis [1, 2, 3, 4, 5]. Most granulomas are discovered because of mass effects causing compression of the pituitary gland and the surrounding tissue structures. Hypopituitarism, hyperprolactinemia, diabetes insipidus and aseptic meningitis are the most usual, but not specific manifestations. In addition, the imaging findings of intrasellar granulomas are usually nonspecific. Mycobacteria other than the tubercle bacillus, representing a novel agent of pituitary granulomas are responsible for 0.15% to 4.0% of intracranial tumors in western countries [6, 7]. These bacteria are usually nonpathogenic for humans, but occasionally cause progressive and potentially destructive diseases. The lung is the most common site of localized NTM infection in nonimmunocompromised patients. The occurrence of CNS infections with NTM in the absence of acquired immunodeficiency syndrome (AIDS) is rare. Indeed, only a single case of NTM infection of the CNS has been reported in a nonimmunosuppressed patient, but without pituitary involvement [8]. In nonimmunosuppressed patients, chronic obstructive pulmonary disease, malignant neoplasm and inherited connective tissue disorders are the most common predisposing factors for development of NTM infectious disease, especially of M. avium complex infection. In our patient none of these predisposing factors were identified. Given the negative results of Z-N stain in pituitary tissue, the diagnosis of NTM infection in our patient was confirmed by nested PCR technique. The PCR method, which was used, is considered to be a powerful tool for diagnosing M. tuberculosis and other NTM infections from paraffin-embedded tissues [9]. PCR analysis has been used in only a single case of a pituitary granuloma so far, which was proved to be due to M. tuberculosis [10] . Although surgical resection is considered to be the treatment of choice for localized NTM infections, combined antimycobacterial therapy is recommended if complete surgical resection is not possible or uncertain [11, 12, 13]. References Bell NH: Endocrine complications of sarcoidosis. Endocr Metab Clin North Am 20:645-654, 1991. Honegger J, Fahlbusch R, Bornemann A, Hensen J, Buchfelder M, Müller M, Nomikos, P: Lymphocytic and granulomatous hypophysitis: Experience with nine cases. Neurosurgery 40:713 -723, 1997. 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