Which statement correctly describes the diagnostic performance of ALP staining for detecting OSA?

• A. Sensitivity 88-100% and Specificity 89-94%
• B. Sensitivity 50-60% and Specificity 60-70%
• C. Sensitivity 10-20% and Specificity 90-95%
• D. Sensitivity 100% and Specificity 0%

Answer: (A)

ALP staining taps into the fact that osteosarcoma cells often produce alkaline phosphatase, a marker of osteoblastic activity. When a test has high sensitivity, it correctly flags most true cases of the disease, and with high specificity, it correctly identifies most cases that are not the disease. For detecting OSA, ALP staining tends to be positive in a large majority of osteosarcomas, giving sensitivity roughly in the 88–100% range, and it correctly yields a negative result in most non-osteosarcoma lesions, giving specificity around 89–94%. This combination makes ALP staining a strong adjunct to standard histology for supporting a diagnosis of osteosarcoma.

Keep in mind that ALP can be expressed in other situations, such as reactive bone formation or certain non-osteogenic processes, so results should always be interpreted alongside the tumor’s morphology and clinical context.