3.2.1 Diagnostic Considerations
This case highlights the importance of an accurate diagnosis and the need for improved familiarity and understanding of vascular anomalies by providers as well as by families and patients. In our patient’s case, the excised “cyst” was a LM, which was confirmed upon review of his prior pathology. While an isolated LM would not raise suspicion for a CLA, this history was an important clue in his final diagnosis. The combination of soft tissue LM, lytic lesions of the ribs and development of a large chylothorax raises suspicion for CLA. Given concern for GLA, MRI of the abdomen, pelvis and spine revealed lesions in the pelvic bone, multiple vertebrae, and spleen as well as the presence of multiple mesenteric and retroperitoneal cysts (Figure 2B) . No cortical bone destruction was evident on imaging. Chest imaging with CT or MRI is also indicated in the workup of possible GLA, which our patient had after chest tube placement. Echocardiogram did not demonstrate pericardial effusion. Given the constellation of these findings, he was diagnosed with GLA.
Bone lesions are a common finding in pediatric and adult patients. Most bone lesions are benign tumors in children. Plain film is the primary modality in the initial evaluation of osseous abnormalities, although diagnosis is not always straight-forward and may require CT or MRI. In many instances, a characteristic radiologic appearance on plain film, along with age of patient, location of the lesion(s) and presenting symptoms, helps differentiate benign from malignant lesions. Benign lesions, including those in CLA, typically demonstrate bone destruction with well-demarcated margins. However, multiple myeloma and metastases must be evaluated for in adults, particularly when older than 40 years of age. In children, the differential diagnoses for multiple sharply defined osteolytic lesions is narrower and includes LCH and multiple enchondromas. Other benign lesions that are generally singular in nature, such as non-ossifying fibroma, chondroblastoma, chondromyxoid fibroma, osteoid osteoma, giant cell tumor, unicameral and aneurysmal bone cysts, also appear radiolucent on plain film but can typically be differentiated from CLA on MRI or CT imaging, if not by plain film. In children with CLA, bone lesions are frequently found incidentally or with pathologic fractures. When bone pain, laboratory abnormalities, or systemic signs and symptoms are present, metastatic neuroblastoma, Ewing’s sarcoma, acute leukemia and osteomyelitis must also be considered. Chronic pain is a frequent presentation in adolescents and adults with CLA.