cryptococcal inflammatory pseudotumor

"Inflammatory pseudotumors" (IPTs) embrace a heterogeneous spectrum of reactive, infective, and neoplastic entities, that are characterized by a clinical mass composed of a histologic proliferation of spindle cells in a background of inflammatory cells and collagen fibers.

Although a spectrum of microorganisms have been identified in infective IPTs, mycobacterial infective IPTs are reported most commonly.

The specimens demonstrate a storiform arrangement of plump spindle cells, in addition to spindle and polygonal cells that are arranged in a haphazard manner.

Background lymphocytes, plasma cells, and fibrosis are noted, in addition to scattered giant cells and focal necrosis.

On high-power examination, Cryptococcus neoformans yeasts are identified within and between vacuolated spindle and polygonal cells on routine and special stains, confirming cryptococcal IPTs.

Immunophenotyping of the spindle cells confirmed a mixed histiocytic and myofibroblastic lineage, with a predominance of the former.

References

 Cryptococcal inflammatory pseudotumors.
Sing Y, Ramdial PK.
Am J Surg Pathol. 2007 Oct;31(10):1521-7.
PMID: 17895752