Table of Contents
Definition / general | Terminology | Sites | Pathophysiology | Clinical features | Case reports | Treatment | Clinical images | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Positive stains | Negative stains | Differential diagnosisCite this page: Avadhani V. Nodular histiocytic hyperplasia. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/pleuranodularhistiohyper.html. Accessed December 4th, 2024.
Definition / general
- Small nodular aggregates of histiocytes with mesothelial cells scattered in the aggregates or in clusters
Terminology
- Nodular mesothelial hyperplasia, mesothelial / monoytc incidental cardiac excrescences (MICE), nodular histiocytic / mesothelial hyperplasia
Sites
- Lesions have been described in lung, pleura, hernia sac, pericardium, peritoneum
Pathophysiology
- Hypothesis: trauma, tumor or inflammation lead to histiocyte / mesothelial expression of CD34 and adhesion molecules, which lead to aggregates of histiocytes and mesothelial cells through cell-cell interactions
Clinical features
- Almost always an incidental finding
Case reports
- 2 year old boy, 23 and 78 year old women, 74 year old man (Am J Surg Pathol 1998;22:285)
- 5 cases: peritoneal, pulmonary, pericardial (Ann Diagn Pathol 2004;8:115)
Treatment
- None required; an incidental finding
Microscopic (histologic) description
- Compact nodular collections of polygonal to oval cells with indistinct cell borders and moderate cytoplasm
- Nuclei are oval to angulated with grooves (usually) and inconspicuous nucleoli
- Mitoses may be present but no atypical mitoses
- Hemosiderin laden macrophages may be present
- Also present are scattered indistinguishable bland cuboidal to polygonal cells with moderate cytoplasm, which show cytokeratin and calretinin staining, indicating their mesothelial origin
Microscopic (histologic) images
Cytology description
- Similar nodular aggregates have also been described in cell block material from serous effusions - this is the most important pitfall in cytodiagnosis of serous effusions (Diagn Cytopathol 2002;26:68)
Positive stains
- Two populations: histiocytes (CD68+), mesothelial cells (cytokeratin+, calretinin+)
Differential diagnosis
- Endometriosis
- Leukemia / lymphoma
- Metastatic adenocarcinoma / carcinoma
- Mesothelioma
- Reactive / florid mesothelial hyperplasia: generalized, in contrast to the localized nodular histiocytic proliferation in this lesion