Final answer:
Based on the symptoms and lab results, including continuous knee pain worsening at night and significantly elevated serum alkaline phosphatase, the APRN should suspect Paget's disease, which is a disorder of bone remodeling causing abnormal and haphazard bone formation.
Step-by-step explanation:
The symptoms and test results presented by the patient, such as pain and swelling in the left knee, pain that has become continuous and worsens at night, elevated serum alkaline phosphatase (ALP) levels, and a computed tomography (CT) scan showing the compact bone replaced with dense callus of masses of osteoid, are indicative of Paget's disease. This condition is diagnosed through imaging studies and lab tests like X-rays, bone scans, and serum ALP levels. It is a bone remodeling disorder predominantly seen in adults over the age of 40.
In Paget's disease, there is an excessive breakdown of bone tissue by overactive osteoclasts followed by an attempt of osteoblasts to compensate, which results in the formation of new bone that is haphazard and weak. This contrasts with conditions like osteoporosis, where there is a decrease in bone mass without the elevated levels of ALP. The information provided does not suggest the typical features of a bone malignancy, but rather the hallmarks of an abnormal bone remodeling process seen in Paget's disease.