From the Guidelines
To exclude malignancy in a patient with bilateral axillary acanthosis nigricans, a comprehensive diagnostic workup including thorough physical examination, laboratory investigations, and imaging studies such as chest X-ray, abdominal and pelvic CT scan or MRI, and upper gastrointestinal endoscopy is necessary. The patient's gradual onset of symptoms over 6 months, absence of constitutional symptoms, and lack of other risk factors aside from smoking, necessitate a careful evaluation to rule out underlying malignancy. Initial laboratory investigations should include complete blood count, comprehensive metabolic panel, fasting glucose, HbA1c, and fasting insulin levels to assess for insulin resistance, as well as tumor markers appropriate for age and sex, including CEA, CA 19-9, CA-125 (in females), and PSA (in males) 1.
Given the patient's presentation, it is crucial to consider the possibility of gastric adenocarcinoma, which is commonly associated with malignant acanthosis nigricans. Therefore, upper gastrointestinal endoscopy is recommended to directly visualize and biopsy any suspicious lesions in the stomach or esophagus. Age-appropriate cancer screening should also be completed, including colonoscopy, mammography for females, and skin examination. In cases where initial investigations are inconclusive but clinical suspicion remains high, a PET-CT scan may help identify occult malignancies, as suggested by the ESMO clinical recommendations for diagnosis, treatment, and follow-up of cancers of unknown primary site 1.
The diagnostic workup should be guided by the principles outlined in the ESMO minimum clinical recommendations for diagnosis, treatment, and follow-up of cancers of unknown primary site, which emphasize the importance of thorough physical examination, basic blood and biochemistry survey, urinalysis, fecal occult blood test, and imaging studies such as chest X-ray and CT scan of the abdomen and pelvis 1. By prioritizing these investigations, clinicians can effectively exclude malignancy and provide appropriate management for patients with bilateral axillary acanthosis nigricans.
Key investigations to exclude malignancy in this patient include:
- Thorough physical examination
- Laboratory investigations: complete blood count, comprehensive metabolic panel, fasting glucose, HbA1c, fasting insulin levels, and tumor markers (CEA, CA 19-9, CA-125, PSA)
- Imaging studies: chest X-ray, abdominal and pelvic CT scan or MRI
- Upper gastrointestinal endoscopy
- Age-appropriate cancer screening: colonoscopy, mammography, skin examination
- PET-CT scan if initial investigations are inconclusive but clinical suspicion remains high.
From the Research
Investigations to Exclude Malignancy
To exclude malignancy in a patient with gradual onset of bilateral axillary acanthosis nigricans (AN) over 6 months, the following investigations are recommended:
- Fasting lipoprotein profile
- Fasting glucose
- Fasting insulin
- Hemoglobin
- Alanine aminotransferase
- Radiological investigations, such as:
- Plain radiography
- Ultrasonography
- Magnetic resonance imaging (MRI)
- Computerized tomography (CT) scan 2 These investigations are necessary to rule out underlying malignancies, as AN can be a paraneoplastic syndrome associated with various types of cancer, including gastric, lung, ovarian, and breast carcinomas 3, 4, 5.
Importance of Screening
Screening for metabolic syndrome and malignancies is crucial in patients with AN, as it can be a red flag for underlying pathologies 3. The combination of AN and skin tags is more often associated with metabolic syndrome, but AN may also be a marker of internal malignancy 3, 5.
Diagnostic Approach
A comprehensive diagnostic approach is necessary to determine the underlying cause of AN, including clinical evaluation, laboratory tests, and imaging studies 2, 6. This approach will help to exclude malignancy and identify any associated conditions, such as metabolic syndrome or other systemic diseases.