Pseudo-pheochromocytoma due to obstructive sleep apnea: a case report

SUMMARY

Obstructive sleep apnea (OSA) is a condition of intermittent nocturnal upper airway obstruction. OSA increases sympathetic drive which may result in clinical and biochemical features suggestive of pheochromocytoma. We present the case of a 65-year-old male with a 2.9-cm left adrenal incidentaloma on CT, hypertension, symptoms of headache, anxiety and diaphoresis, and persistently elevated 24-h urine norepinephrine (initially 818 nmol/day (89-470)) and normetanephrine (initially 11.2 µmol/day (0.6-2.7)). He was started on prazosin and underwent left adrenalectomy. Pathology revealed an adrenal corticoadenoma with no evidence of pheochromocytoma. Over the next 2 years, urine norepinephrine and normetanephrine remained significantly elevated with no MIBG avid disease. Years later, he was diagnosed with severe OSA and treated with continuous positive airway pressure. Urine testing done once OSA was well controlled revealed complete normalization of urine norepinephrine and normetanephrine with substantial symptom improvement. It was concluded that the patient never had a pheochromocytoma but rather an adrenal adenoma with biochemistry and symptoms suggestive of pheochromocytoma due to untreated severe OSA. Pseudo-pheochromocytoma is a rare presentation of OSA and should be considered on the differential of elevated urine catecholamines and metanephrines in the right clinical setting.

LEARNING POINTS

Obstructive sleep apnea (OSA) is a common condition among adults. OSA may rarely present as pseudo-pheochromocytoma with symptoms of pallor, palpitations, perspiration, headache, or anxiety. OSA should be considered on the differential of elevated urine catecholamines and metanephrines, especially in patients with negative metaiodobenzylguanidine (MIBG) scan results.

Modulatory effect of methanol extract of Annona muricata stem bark on mitochondrial membrane permeability transition pore in normal rat liver and monosodium glutamate-induced uterine hyperplasia

OBJECTIVES

Uterine fibroids are benign tumors that develop in many women of reproductive age. Surgery is the main approach to treatment while other options are also associated with adverse effects. Studies have shown that certain bioactive agents present in medicinal plants elicit their anti-tumor activity by induction of mitochondrial permeability transition (mPT) opening. This research therefore aimed at investigating the effect of methanol extract of Annona muricata (MEAM) on mPT pore opening in normal and monosodium glutamate-induced uterine hyperplasia using female Wistar rats.

METHODS

Mitochondria, isolated from rat liver were exposed to different concentrations (20, 60, 100, 140 and 180 μg/mL) of MEAM. The mPT pore opening, cytochrome c release, mitochondrial ATPase (mATPase) activity and the percentage lipid peroxidation were assessed spectrophotometrically. Histological effects of MEAM on the liver, brain and uterus of normal and MSG-treated rats were investigated.

RESULTS

The in vitro results showed a significant induction of mPT pore opening by 2.4, 4.2 and 6.4 folds, release of cytochrome c and enhancement of mATPase activity at 100,140 and 180 μg/mL, respectively. However, oral administration of MEAM did not induce mPT pore opening, neither any significant release of cytochrome c nor enhancement of mATPase activity at all the dosages used. However, histological assay revealed the presence of MSG-induced cellular damage and uterine hyperplasia which was ameliorated by MEAM co-administration.

CONCLUSIONS

These findings suggest that MEAM contains phytochemicals that can ameliorate MSG-induced damage and uterine hyperplasia in rats; however, the mechanism might not be via upregulation of mitochondrial-mediated apoptosis.

3-(Para-fluorobenzoyl)-propionic acid; a metabolite of haloperidol, reversed oestradiol valerate-induced uterine hyperplasia via modulation of oestrogen receptor signalling pathways in female Wistar rats

Background 3-(Para-fluorobenzoyl)-propionic acid (3PFBPA) is one of the metabolites of haloperidol used in the treatment of psychotic disorders. 3PFBPA is an inhibitor of mitogen-activated protein kinase (MAPK), implicated in the development of uterine fibroids (UFs) and cellular proliferation. In this study, the effect of 3PFBPA on oestradiol valerate (OV)-induced uterine hyperplasia was investigated. Methods Uterine hyperplasia was induced by intraperitoneal (i.p.) injection of OV (3 mg/kg for 12 weeks). Expression of oestrogen receptor (ER) α, β-catenin and E-cadherin were investigated via immunohistochemistry. The histology and fibroblast cell count/μm2 (using histomorphometry) were carried out. Results There was a significant increase in the levels of oestrogen, progesterone and total cholesterol in the OV-treated group when compared with the control, assessed by enzyme-linked immunosorbent assay (ELISA) kits. Oestrogen and total cholesterol were markedly reduced in the OV + 3PFBPAtreated group when compared with the OV-treated group. The OV-induced overexpression of β-catenin and ER were also ameliorated by 3PFBPA. Also, the loss of E-cadherin function in the OV-treated group was restored by 3PFBPA. The histological findings and histomorphometric results revealed the presence of uterine hyperplasia in the OV-treated rats which was significantly reversed by 3PFBPA. Histological studies revealed a protective role against OV-induced uterine damage that was found after OV + 3PFBPA co-administration. Conclusion This study demonstrated that 3PFBPA ameliorates OV-induced uterine hyperplasia in the female Wistar rat model. The findings warrant further investigation of the antifibrotic effects of 3PFBPA in humans.

Uterine double-conditional inactivation of Smad2 and Smad3 in mice causes endometrial dysregulation, infertility, and uterine cancer

SMAD2 and SMAD3 are downstream proteins in the transforming growth factor-β (TGF β) signaling pathway that translocate signals from the cell membrane to the nucleus, bind DNA, and control the expression of target genes. While SMAD2/3 have important roles in the ovary, we do not fully understand the roles of SMAD2/3 in the uterus and their implications in the reproductive system. To avoid deleterious effects of global deletion, and given previous data showing redundant function of Smad2 and Smad3, a double-conditional knockout was generated using progesterone receptor-cre (Smad2/3 cKO) mice. Smad2/3 cKO mice were infertile due to endometrial hyperproliferation observed as early as 6 weeks of postnatal life. Endometrial hyperplasia worsened with age, and all Smad2/3 cKO mice ultimately developed bulky endometrioid-type uterine cancers with 100% mortality by 8 months of age. The phenotype was hormone-dependent and could be prevented with removal of the ovaries at 6 weeks of age but not at 12 weeks. Uterine tumor epithelium was associated with decreased expression of steroid biosynthesis genes, increased expression of inflammatory response genes, and abnormal expression of cell cycle checkpoint genes. Our results indicate the crucial role of SMAD2/3 in maintaining normal endometrial function and confirm the hormone-dependent nature of SMAD2/3 in the uterus. The hyperproliferation of the endometrium affected both implantation and maintenance of pregnancy. Our findings generate a mouse model to study the roles of SMAD2/3 in the uterus and serve to provide insight into the mechanism by which the endometrium can escape the plethora of growth regulatory proteins.