Endocrine paraneoplastic syndromes in patients with neuroendocrine neoplasms

Paraneoplastic neuropathies and peripheral nerve hyperexcitability disorders

Peripheral neuropathy is a common referral for patients to the neurologic clinics. Paraneoplastic neuropathies account for a small but high morbidity and mortality subgroup. Symptoms include weakness, sensory loss, sweating irregularity, blood pressure instability, severe constipation, and neuropathic pain. Neuropathy is the first presenting symptom of malignancy among many patients. The molecular and cellular oncogenic immune targets reside within cell bodies, axons, cytoplasms, or surface membranes of neural tissues. A more favorable immune treatment outcome occurs in those where the targets reside on the cell surface. Patients with antibodies binding cell surface antigens commonly have neural hyperexcitability with pain, cramps, fasciculations, and hyperhidrotic attacks (CASPR2, LGI1, and others). The antigenic targets are also commonly expressed in the central nervous system, with presenting symptoms being myelopathy, encephalopathy, and seizures with neuropathy, often masked. Pain and autonomic components typically relate to small nerve fiber involvement (nociceptive, adrenergic, enteric, and sudomotor), sometimes without nerve fiber loss but rather hyperexcitability. The specific antibodies discovered help direct cancer investigations. Among the primary axonal paraneoplastic neuropathies, pathognomonic clinical features do not exist, and testing for multiple antibodies simultaneously provides the best sensitivity in testing (AGNA1-SOX1; amphiphysin; ANNA-1-HU; ANNA-3-DACH1; CASPR2; CRMP5; LGI1; PCA2-MAP1B, and others). Performing confirmatory antibody testing using adjunct methods improves specificity. Antibody-mediated demyelinating paraneoplastic neuropathies are limited to MAG-IgM (IgM-MGUS, Waldenström's, and myeloma), with the others associated with cytokine elevations (VEGF, IL6) caused by osteosclerotic myeloma, plasmacytoma (POEMS), and rarely angiofollicular lymphoma (Castleman's). Paraneoplastic disorders have clinical overlap with other idiopathic antibody disorders, including IgG4 demyelinating nodopathies (NF155 and Contactin-1). This review summarizes the paraneoplastic neuropathies, including those with peripheral nerve hyperexcitability.

Severe hypercalcemia due to metastatic pancreatic neuroendocrine tumor: a case report

BACKGROUND

Hypercalcemia of malignancy, as a paraneoplastic syndrome, is the most common metabolic disorder that accounts for 30% of malignancies and usually has a poor prognosis. Neuroendocrine tumors are uncommon and arise from neuroendocrine cells throughout the body. Actually, paraneoplastic hypercalcemia in neuroendocrine tumors is unusual and mostly associated with parathyroid hormone-related protein (PTHrP) secretion.

CASE PRESENTATION

We report a 51-year-old Iranian man who presented with nausea, vomiting, and significant weight loss for 1 month. Laboratory data revealed calcium of 26 mg/dl, accompanied by low level of PTH. Octreotide scan revealed a large donut-shaped octreotide avid lesion in the epigastric region at the right side of the mid-abdomen, with multiple varying size foci of abnormally increased radiotracer uptake in the epigastric region and both lobes of the liver. Endoscopic ultrasonography demonstrated a large heterogeneous mass lesion with irregular outline and good demarcation in the body of the pancreas with diffuse foci of calcification. Percutaneous biopsy of the liver mass demonstrated a well-differentiated neuroendocrine tumor (low grade) confirmed by immunohistochemistry with strongly positive chromogranin and synaptophysin stain. Hypercalcemia was treated with hydration, few sessions of hemodialysis, calcitonin, and denosumab injection. However, the patient developed symptomatic hypocalcemia. Oncology consultation led to prescription of long-acting octreotide 30 mg monthly and everolimus daily.

CONCLUSION

Pancreatic neuroendocrine tumor could lead to malignant hypercalcemia; secretion of PTHrP is the most common cause, and signs and symptoms are usually milder than paraneoplastic syndrome due to hematologic and solid tumor. Generally, survival is better; however, its treatment is challenging, and primary debulking surgery is often required. A team approach to management is important at all points.

What Lies behind Paraneoplastic Hypercalcemia Secondary to Well-Differentiated Neuroendocrine Neoplasms? A Systematic Review of the Literature

BACKGROUND

Neuroendocrine neoplasms (NEN) originate from neuroendocrine cells ubiquitously spread throughout the body. Hypercalcemia associated with cancer is the most common life-threatening metabolic disorder in patients with advanced stage cancer. Paraneoplastic hypercalcemia is more commonly associated with hematological malignancies, renal and breast carcinomas, and squamous cell carcinomas, but it has also been described in patients with well-differentiated NEN, where it often remains undiagnosed. Among its causes, systemic secretion of parathyroid hormone-related protein (PTHrP) and ectopic production of 1,25-dihydroxyvitamin D and parathyroid hormone (PTH) may be considered paraneoplastic causes of hypercalcemia. In order to clarify the diagnostic work up of paraneoplastic hypercalcemia in patients with NEN, we perform a systematic review, which is lacking in the literature.

METHODS

We performed a data search using MEDLINE and SCOPUS including papers from 1961 to 2021. We selected articles on paraneoplastic hypercalcemia associated with well-differentiated NEN.

RESULTS

The search led to the selection of 78 publications for a total of 114 patients. Pooled data showed that the most frequent primary tumor site associated with paraneoplastic hypercalcemia was pancreatic NEN, followed by Pheochromocytoma. In most cases, paraneoplastic hypercalcemia was caused by PTHrP production and secretion. In more than two thirds of cases, paraneoplastic hypercalcemia was present at the time of NEN diagnosis and, in metachronous cases, was related to local recurrence, distant metastasis development, or tumor progression. In most patients, a combination of therapeutic approaches was employed, and reduction of the tumor burden was essential to control the paraneoplastic syndrome.

DISCUSSION

The onset of hypercalcemia associated with cancer in patients with well-differentiated NEN represents a major clinical challenge. The complex clinical and therapeutical management of paraneoplastic hypercalcemia implies the need for a multidisciplinary approach, aimed at controlling the clinical syndrome and tumor growth.

Endocrine abnormality in paraneoplastic syndrome

Paraneoplastic syndromes denote rare but notable phenomena caused by the tumour mediated release of bioactive substances. Peptide and non-peptide hormone causes are explored with a particular focus on pathogenesis, symptoms, diagnosis and treatment. Early detection and management of paraneoplastic syndromes can improve morbidly and mortality; definitive treatment remains effective surgical or anti-tumour therapies. Pituitary autoimmunity may provide a novel presentation of paraneoplastic syndromes for which further research is warranted.

Cushing's syndrome due to adrenocorticotropic hormone-secreting metastatic neuroendocrine tumor of unknown primary origin: a case report and literature review

BACKGROUND

In this article, we present a case of neuroendocrine neoplasm of unknown primary origin (UPO NEN), which is a rare cause of ectopic Cushing's syndrome (ECS) presenting numerous challenges, together with a literature review.

CASE REPORT

A 43-year-old male patient presented with clinical features consistent with Cushing's syndrome (CS) and adrenocorticotropic hormone (ACTH)-dependent hypercortisolemia. Despite a suspicious lesion on pituitary MRI, the high-dose dexamethasone suppression test and bilateral inferior petrosal sinus sampling results were not compatible with Cushing's disease. Bilateral non-homogeneous opacities were observed in the thorax CT of the patient, who also had a history of COVID-19 infection, but no tumoral lesion was detected. When ⁶⁸Ga-SSTR PET/CT and ¹⁸FDG-PET/CT were performed, multiple metastatic foci were detected in mediastinal and hilar lymph nodes and the axial skeleton. Paratracheal-subcarinal lymph nodes were excised mediastinoscopically, and the diagnosis of NEN was made. Histopathological findings indicated that the possible origin was an atypical pulmonary carcinoid with a low Ki-67 labeling index. After controlling hypercortisolemia, a regimen of somatostatin analogs and capecitabine plus temozolomide was decided upon as treatment by a multidisciplinary council.

CONCLUSION

This is a challenging case of UPO NEN presenting with ECS and confounding factors, such as previous infection and incidental lesions, during the diagnosis process. The case in question highlighted the fact that atypical pulmonary carcinoid with a low proliferation index may cause visible metastases even when radiologically undetectable.

Calcitonin-secreting neuroendocrine neoplasms of the lung: a systematic review and narrative synthesis

Calcitonin-secreting neuroendocrine neoplasms of the lung are rare, with few cases reported in the literature. Differentiating between medullary thyroid carcinoma and an ectopic source of calcitonin secretion can represent a complex diagnostic conundrum for managing physicians, with cases of unnecessary thyroidectomy reported in the literature. This manuscript reports a case of ectopic hypercalcitonaemia from a metastatic neuroendocrine neoplasm of the lung with concurrent thyroid pathology and summarises the results of a systematic review of the literature. Medical Literature Analysis and Retrieval System Online, Excerpta Medica, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov and SCOPUS databases were systematically and critically appraised for all peer reviewed manuscripts that suitably fulfilled the inclusion criteria established a priori. The protocol for this systematic review was developed according to the Preferred Reporting Items for Systematic review and Meta-Analysis Protocols, and followed methods outlined in The Cochrane Handbook for Systematic Reviews of Interventions. This systematic review is registered with PROSPERO. It is vital to consider diagnoses other than medullary thyroid carcinoma when presented with a patient with raised calcitonin, as it is not pathognomonic of medullary thyroid carcinoma. Lung neuroendocrine neoplasms can appear similar to medullary thyroid carcinoma histologically, they can secrete calcitonin and metastasize to the thyroid. Patients with medullary thyroid carcinoma may show stimulated calcitonin values over two or more times above the basal values, whereas calcitonin-secreting neuroendocrine neoplasms may or may not show response to stimulation tests. The present review summarises existing evidence from cases of ectopic hypercalcitonaemia to lung neuroendocrine neoplasms.

Lung neoplasm mimicking as ectopic pregnancy due to paraneoplastic secretion of human chorionic gonadotropin: a case report and literature review

PURPOSE

The present systematic review aimed to examine the relationship between lung neoplasm and human chorionic gonadotropin (HCG). Especially, women with lung neoplasm mimicking as ectopic pregnancy were explored.

METHODS

A rare case of lung neoplasm with high serum β-HCG, which was initially thought to be ectopic pregnancy, was reported. A literature search was performed of the US National Library of Medicine (MEDLINE), EMBASE, PubMed, and the Cochrane Database of Systematic Reviews using appropriate keywords and subject headings to February 2020.

RESULTS

Studies assessed lung neoplasm patients with positive HCG were included. Twenty studies, including 24 patients, were included. These cases illustrate the importance of considering the possibility of paraneoplastic secretion of β-HCG in patients who have a positive pregnancy test. This may prevent a delay in the diagnosis and treatment of malignancy in young women. Of the 24 cases, only 7 (29.17%) were managed surgically; others were managed conservatively or with chemotherapy or radiation.

CONCLUSION

The present systematic review shows the need to re-awaken awareness and high index of suspicion to lung neoplasm diagnosis in patients with positive pregnancy test.

Case Report: Unmasking Hypercalcemia in Patients With Neuroendocrine Neoplasms. Experience From Six Italian Referral Centers

BACKGROUND

Hypercalcemia is a common paraneoplastic syndrome which can occur in up to 10% of patients with advanced neoplasms. Paraneoplastic parathyroid hormone-related protein (PTHrP) represents the most frequent cause of this syndrome. In neuroendocrine neoplasms (NENs) paraneoplastic hypercalcemia is rare.

CASE SERIES

The present series includes all patients with NENs and paraneoplastic hypercalcemia from four Italian centres: (I) A 40-year-old man was hospitalized for repeated episodes of falls, hyposthenia and drowsiness. Severe hypercalcemia was found. Metastatic pancreatic G2 NEN and PTHrP-related hypercalcemia were diagnosed. The patient started therapy with somatostatin analogs (SSA) and Denosumab. After disease progression peptide receptor radionuclide therapy (PRRT) was started with an objective response associated with PTHrP reduction and normocalcemia. (II) A 45-year-old man was referred for pancreatic G2 NEN. SSA and subsequently everolimus were administered for metastases occurrence. Hypercalcemia occurred and PRRT and Denosumab were started for disease progression with the onset of bone metastases. Despite disease stability after four cycles of PRRT the patient's performance status worsened until death. (III) A 49-year-old woman was hospitalized for psychic slowdown, confusional state, sensory dullness. A severe hypercalcemia, associated with a pancreatic G1 NEN was diagnosed and treated with haemodialysis, bisphosphonates injections and continuous infusion of calcitonin. 1,25-dihydroxyvitamin D was high, PTHrP was undetectable. After surgery serum calcium levels and 1,25-dihydroxyvitamin D were normalized. (IV) A 69-year-old man was hospitalized after the onset of shortness of breath and dyspnea, asthenia and weight loss. Computed Tomography (CT) and ⁶⁸Ga DOTATOC Positron Emission Tomography (PET)-CT revealed a left pulmonary nodule. Hypercalcemia and markedly elevated PTHrP levels were detected. The histological examination revealed an atypical carcinoid. After surgery, calcium levels were normalized, PTHrP was significantly reduced with an improvement of general conditions.

CONCLUSION

In our series, paraneoplastic PTHrP-related hypercalcemia occurred in pancreatic NEN and in one bronchial carcinoid representing the third case in the literature. Our case associated with 1,25-dihydroxyvitamin D secretion represents the fourth case in the literature. PTHrP secretion should be considered in NENs' patients with hypercalcemia. Acute treatment should be focused on lowering calcium levels, and long-term control can be achieved by tumor cytoreduction inhibiting PTHrP release.