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University of Melbourne, Parkville, Victoria, Australia
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Summary
Acanthosis nigricans (AN) is a common dermatosis associated with hyperinsulinemia and insulin resistance. However, AN has been rarely reported in patients with insulinoma, a state of persistent hyperinsulinemia. We present a case of metastatic insulinoma, in whom AN manifested after the first cycle of peptide receptor radionuclide therapy (PRRT). A 40-year-old man was diagnosed with metastatic insulinoma after 5 months of symptomatic hypoglycemia. Within 1 month post PRRT, the patient became euglycemic but developed a pigmented, pruritic rash which was confirmed on biopsy as AN. We discuss the rare manifestation of AN in subjects with insulinoma, the role of insulin in the pathogenesis of AN, malignant AN in non-insulin-secreting malignancies and association with other insulin-resistant endocrinopathies such as acromegaly.
Learning points
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Acanthosis nigricans (AN) is a common dermatosis which is typically asymptomatic and associated with the hyperinsulinemic state.
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Malignant AN can rapidly spread, cause pruritus and affect mucosa and the oral cavity.
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AN is extremely rare in patients with insulinoma despite marked hyperinsulinemia.
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Peptide receptor radionuclide therapy might have triggered TGF-α secretion in this subject which led to malignant AN.
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Rapid spread or unusual distribution of pruritic AN warrants further investigation to exclude underlying malignancy.
Faculty of Medicine, The University of Queensland, Brisbane, Australia
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Faculty of Medicine, The University of Queensland, Brisbane, Australia
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Department of Radiology, Royal Brisbane and Women’s Hospital, Brisbane, Australia
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Faculty of Medicine, The University of Queensland, Brisbane, Australia
Institute of Health and Biomedical Innovation, Faculty of Health, Queensland University of Technology, Translational Research Institute, Princess Alexandra Hospital, Brisbane Australia
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Summary
A 34-year-old woman presented 18 months post-partum with blurred vision, polyuria, amenorrhoea, headache and general malaise. Comprehensive clinical examination showed left superior temporal visual loss only. Initial investigations revealed panhypopituitarism and MRI demonstrated a sellar mass involving the infundibulum and hypothalamus. Lymphocytic hypophysitis was suspected and high dose glucocorticoids were commenced along with desmopressin and thyroxine. However, her vision rapidly deteriorated. At surgical biopsy, an irresectable grey amorphous mass involving the optic chiasm was identified. Histopathology was initially reported as granulomatous hypophysitis. Despite the ongoing treatment with glucocorticoids, her vision worsened to light detection only. Histopathological review revised the diagnosis to partially treated lymphoma. A PET scan demonstrated avid uptake in the pituitary gland in addition to splenic involvement, lymphadenopathy above and below the diaphragm, and a bone lesion. Excisional node biopsy of an impalpable infraclavicular lymph node confirmed nodular lymphocyte-predominant Hodgkin lymphoma. Hyper-CVAD chemotherapy was commenced, along with rituximab; fluid-balance management during chemotherapy (with its requisite large fluid volumes) was extremely complex given her diabetes insipidus. The patient is now in clinical remission. Panhypopituitarism persists; however, her vision has recovered sufficiently for reading large print and driving. To the best of our knowledge, this is the first reported case of Hodgkin lymphoma presenting initially as hypopituitarism.
Learning points
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Lymphoma involving the pituitary is exceedingly rare and, to the best of our knowledge, this is the first reported case of nodular lymphocyte-predominant Hodgkin lymphoma presenting as hypopituitarism.
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There are myriad causes of a sellar mass and this case highlights the importance of reconsidering the diagnosis when patients fail to respond as expected to appropriate therapeutic intervention.
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This case highlights the difficulties associated with managing panhypopituitary patients receiving chemotherapy, particularly when this involves large volumes of i.v. hydration fluid.
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Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
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Summary
Succinate dehydrogenase deficiency has been associated with several neoplasias, including renal cell carcinoma (RCC) and those associated with hereditary paraganglioma (PGL)/ pheochromocytoma (PHEO) syndromes, Carney dyad, and Carney triad. Carney triad is a rare multitumoral syndrome characterized by co-existing PGL, gastrointestinal stromal tumor (GIST), and pulmonary chondroma (CHO). We report a case of a 57-year-old male who presented with para-aortic and gastroesophogeal masses, and a right renal superior pole lesion, which were classified as multiple PGLs, a GIST, and a clear cell renal carcinoma, respectively, on pathology following surgical resection. Additionally, a CHO was diagnosed radiologically, although no biopsy was performed. A diagnosis of Carney triad was made. SDHB immunohistochemical staining was negative for the PGL and the GIST, indicating SDH-deficiency. Interestingly, the renal cell carcinoma (RCC) stained positive for both SDHB and SDHA. Subsequent genetic screening of SDH subunit genes revealed a germline inactivating heterozygous SDHA pathogenic variant (c.91 C>T, p.R31X). Loss of heterozygosity was not detected at the tumor level for the RCC, which likely indicated the SDHA variant would not be causative of the RCC, but could still predispose to the development of neoplasias. To the knowledge of the authors this is the first reported case of an SDHA pathogenic variant in a patient with Carney triad complicated by RCC.
Learning points
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The succinate dehydrogenase enzyme is encoded by four subunit genes (SDHA, SDHB, SDHC, and SDHD; collectively referred to as SDHx), which have been implicated in several neoplasias and are classified as tumor suppressor genes.
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Carney triad is a rare multiple-neoplasia syndrome presenting as an association of PGLs, GISTs, and CHOs.
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Carney triad is most commonly associated with hypermethylation of SDHC as demonstrated in tumor tissue, but approximately 10% of cases are due to pathogenic SDHx variants.
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Although SDHB pathogenic variants are most commonly reported in SDH-deficient renal cell carcinoma, SDHA disease-causing variants have been reported in rare cases.
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Department of Medicine, Monash University, Melbourne, Australia
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Summary
Insulinomas are rare neuroendocrine tumours that classically present with fasting hypoglycaemia. This case report discusses an uncommon and challenging case of insulinoma soon after upper gastrointestinal surgery. A 63-year-old man presented with 6 months of post-prandial hypoglycaemia beginning after a laparoscopic revision of Toupet fundoplication. Hyperinsulinaemic hypoglycaemia was confirmed during a spontaneous episode and in a mixed-meal test. Localisation studies including magnetic resonance imaging (MRI), endoscopic ultrasound (EUS) and gallium dotatate positron emission tomography (68Ga Dotatate PET) were consistent with a small insulinoma in the mid-body of the pancreas. The lesion was excised and histopathology was confirmed a localised well-differentiated neuroendocrine pancreatic neoplasm. There have been no significant episodes of hypoglycaemia since. This case highlights several key points. Insulinoma should be sought in proven post-prandial hyperinsulinaemic hypoglycaemia – even in the absence of fasting hypoglycaemia. The use of nuclear imaging targeting somatostatin and GLP1 receptors has improved accuracy of localisation. Despite these advances, accurate surgical resection can remain challenging.
Learning points:
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Hypoglycaemia is defined by Whipple’s triad and can be provoked by fasting or mixed-meal tests.
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Although uncommon, insulinomas can present with post-prandial hypoglycaemia.
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In hypoglycaemia following gastrointestinal surgery (i.e. bariatric surgery or less commonly Nissen fundoplication) dumping syndrome or non-insulinoma pancreatogenous hypoglycaemia syndrome (NIPHS) should be considered.
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Improved imaging techniques including MRI, endoscopic ultrasound and functional nuclear medicine scans aid localisation of insulinomas.
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Despite advances in imaging and surgical techniques, accurate resection of insulinomas remains challenging.
