What is a rhomboid muscle collection?

Rhomboid Collection: Definition and Clinical Significance

A rhomboid collection refers to crystal deposits with rhomboid (diamond or parallelogram) shapes that can be found in various tissues, most commonly observed in renal pathology as light-chain crystals in conditions like monoclonal gammopathy of renal significance (MGRS).

Types and Locations of Rhomboid Collections

Rhomboid-shaped collections are primarily identified through electron microscopy and can be found in different anatomical locations:

• Renal tissue: Most commonly documented in:

  • Proximal tubular cells as light-chain crystals in crystalline light-chain proximal tubulopathy 1
  • Interstitial infiltrating histiocytes in crystal-storing histiocytosis 1

• Musculoskeletal system: The term may also refer to:

  • Collections of fluid or blood in the rhomboid muscle area following injury 2
  • Tears in the rhomboid major or minor muscles that may require surgical intervention 2

Diagnostic Imaging and Identification

Rhomboid collections are typically identified through:

• Electron microscopy: The gold standard for identifying crystalline deposits with rhomboid shapes 1

  • Appears as moderately electron-dense, light-chain crystals with rod and rhomboid shapes
  • Often found free within the cytoplasm, not membrane-bound
  • Original magnification typically at ×2,700 to ×4,200 for proper visualization

• MRI: For musculoskeletal rhomboid collections (tears or fluid collections) 2

  • Can reveal tears in the rhomboid major at its insertion
  • Helps identify muscle retraction and associated pathology

Clinical Significance

The clinical significance of rhomboid collections varies based on their location and underlying cause:

In Renal Pathology:

• Indicates potential monoclonal gammopathy of renal significance (MGRS) 1
• Associated with conditions like crystalline light-chain proximal tubulopathy
• May lead to kidney dysfunction if untreated

In Musculoskeletal Context:

• Rhomboid muscle tears can present with periscapular pain and scapular dyskinesis 2
• May cause winging of the medial border of the scapula with lateral rotation of its inferior angle 3
• Can result in persistent medial scapular pain requiring surgical intervention 2

Management Considerations

Management depends on the type and location of the rhomboid collection:

• Renal rhomboid collections: Treatment focuses on the underlying monoclonal gammopathy 1

• Musculoskeletal rhomboid collections:

  • Conservative treatment initially with physical therapy 2
  • Surgical repair may be necessary for complete tears with muscle retraction 2
  • Specific techniques include creating bone holes on the medial border of the scapula and repairing the torn muscle using Krackow stitch technique 2
  • Counterstrain techniques may be beneficial for rhomboid tender points 4

Key Takeaways

• Rhomboid collections most commonly refer to crystal deposits with diamond/parallelogram shapes seen in renal pathology
• They are best identified through electron microscopy at appropriate magnification
• These collections have significant clinical implications for diagnosis and management of conditions like MGRS
• In musculoskeletal contexts, rhomboid collections may refer to pathology of the rhomboid muscles requiring specific diagnostic and therapeutic approaches