Persistent sweet taste dysgeusia diagnosed with probable SIADH: Unmasking underlying lung cancer in a high-risk individual: A case report (2024)

Type of publication:
Journal article

*Praveenkumar Katarki, *Nawaid Ahmad, *Lyudmyla Nod

Clinical Medicine 2024. Volume 24, Supplement, April 2024

Introduction: The timely identification of lung cancer is critical but difficult due to its broad and often nonspecific symptoms. This case report highlights the importance of taking into consideration unusual manifestations, especially in persons at high risk, and emphasises the necessity of a thorough diagnostic approach. Case presentation: A 66-year-old female referred from the general practitioner (GP)to the same day emergency care (SDEC) with persistent sweet taste dysgeusia, headache and hyponatraemia (118). Notably, her chest X-ray was unremarkable (image 1) despite a 30-pack-year smoking history. Initial suspicion was on drug-induced syndrome of inappropriate antidiuretic hormone secretion (SIADH) potentially due to her long-term use of gabapentin (for 25 years), as reported in a retrospective study conducted in Sweden.1 However, an inadequate response to treatment prompted further investigation, CT thorax (image 2) revealing primary lung malignancy with liver metastases. A histological evidence is awaited, the radiological diagnosis of the lung cancer was considered after discussion at Lung cancer at the multidisciplinary team. Discussion: This case further strengthens the growing body of evidence suggesting sweet taste dysgeusia as a rare paraneoplastic symptom of small cell lung cancer (SCLC), as documented in previous studies.2–5 The potential mechanisms underlying this phenomenon remain unclear, but possibilities include ectopic antidiuretic hormone (ADH) production4, tumour-derived substances affecting taste pathways5 or metabolic disturbances associated with the malignancy itself.4,5 This case underscores the critical need for heightened suspicion for malignancy, especially in high-risk individuals like smokers, even when presenting with seemingly common diagnoses like SIADH. Additionally, it highlights the limitations of solely relying on initial symptoms and investigations. Notably, the patient had an unremarkable chest X-ray (image 1) despite a significant 40-pack-year smoking history, emphasising the importance of employing a comprehensive diagnostic approach. This approach should encompass a detailed medical history and risk factor evaluation, thorough physical examination for potential malignancy signs, targeted laboratory investigations including electrolytes, renal function, and tumour markers, and appropriate imaging studies based on clinical suspicion and initial findings (chest X-ray, CT scan). While this case showcases the potential of sweet taste dysgeusia as a paraneoplastic sign, several limitations must be acknowledged. First, this symptom remains rare and its specificity for SCLC is uncertain; Second, potential selection bias towards atypical presentations could overestimate its prevalence.7 Finally, confounding factors like hyponatraemia itself can affect taste perception.4. Conclusion: This case contributes to the growing evidence suggesting sweet taste dysgeusia could be an atypical early warning sign of lung cancer, particularly in high-risk individuals. While limitations exist and further research is warranted, this association necessitates further investigation due to its potential implications for earlier detection and improved patient outcomes. Recognising limitations, advocating for further research, and emphasising potential clinical impact contribute to ongoing efforts in improving lung cancer diagnosis and management.

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