Castleman Disease of the Abdomen and Pelvis

Castleman disease is a rare, idiopathic disease characterized by atypical proliferation of lymphocytes. Although almost always benign, a rare, potentially fatal systemic form has been identified. Castleman disease may represent a response to chronic inflammation or a hamartoma of the lymph system, depending on who you believe.

It is most commonly found in the mediastinum (70% of case), but can be found in the neck (10%), pelvis (5%), or axilla (2%). It most commonly manifests as a localized mass or masses.

Three types have been defined histologically:

• Hyaline-vascular type: 90% of cases. 70% younger than 30. Usually asymptomatic
• Plasma cell type: 50% symptomatic (fever, elevated ESR, anemia, hypergammaglobulinemia, and splenomegaly).
• Mixed type.

Imaging findings in the mediastinum differ by histology, but all forms show enhancement. The hyaline-vascular type may present as a solitary, noninvasive mass; a dominant infiltrative mass with associated lymphadenopathy; or a matted lymphadenopathy without a dominant mass. The plasma cell type presents as a diffuse mediastinal lymphadenopathy.

In the pelvis the lesions may be located in the retroperitoneum, mesentery, porta hepatis, or pancreas. On imaging, there is a well-defined, focal enhancing mass that shows homogeneous contrast enhancement when small (< 5cm) or heterogeneous enhancement when large. Unlike mediastinal lesions, no difference is seen between the different types in the pelvis. A single case of an enhancing retroperitoneal mass with infiltration of the surrounding fat has been reported.

Calcifications may be seen in different patterns: Punctate, coarse, peripheral, or "arborizing."

Here we see a right lower quadrant mass, picked up on physical examination, seen on x-ray and further investigated by ultrasound and CT. The differential diagnosis of an enhancing retroperitineal mass such as this is:

• Lymphoma: Enlarged nodes bilaterally. Confluent soft tissue mantle of nodes surrounding aorta and inferior vena cava. Nodes may displace aorta from spine, unusual for other nodal mets
• Metastasis
• Infection: Abscess, tuberculosis.
• Sarcoma: Large RP mass with or without necrotic or cystic degeneration
• Schwannoma
• Paraganglioma
• Hemangiopericytoma
• Inflammatory pseudotumor: Heterogeneous mass. Nonenhancing, heterogeneous enhancement, or peripheral enhancement. May have central hypoattenuation due to necrosis in larger lesions. May have Central calcifications.
• Castleman

References