Erdheim-Chester disease diagnosed by ^99mTc-MDP bone scintigraphy and brief literature review

Area of Science:

• Histiocytosis and Cellular Biology
• Rare Diseases
• Diagnostic Pathology

Background:

• Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis characterized by lipid-laden macrophages and fibrosis.
• It is a multisystemic disorder with common sclerotic bone involvement, particularly in the distal femur and proximal/distal tibia.

Observation:

• A 40-year-old woman presented with systemic symptoms including knee pain, polyuria, and polydipsia over two years.
• Initial bone scintigraphy showed a "hot knee" pattern, leading to a femur biopsy for suspected hematologic malignancy, which revealed only intense fibrosis.
• A year later, bone scintigraphy displayed characteristic ECD bone involvement, and subsequent biopsies, initially showing fibrosis, confirmed histiocytes after CD-68 immunohistochemical staining.

Findings:

• Erdheim-Chester disease diagnosis was delayed due to initial biopsy findings.
• Immunohistochemical staining (CD-68) was crucial for identifying histiocytes, confirming the ECD diagnosis.
• The case highlights the diagnostic challenges associated with ECD, especially when initial pathological findings are non-specific.

Implications:

• This case underscores the importance of considering rare diseases like ECD in patients with suggestive systemic symptoms and bone findings.
• It emphasizes the critical role of advanced diagnostic techniques, such as immunohistochemistry, in confirming diagnoses that may be missed by standard histological examination.
• Early and accurate diagnosis of ECD is vital for appropriate management and improving patient outcomes.