Case of the Month

A renal tumor was resected from a 30-year-old African-American woman. Several histologic patterns were identified, including a reticular and a solid pattern, both shown here. What is the most likely diagnosis? A. Papillary renal cell carcinoma
B. Tubulocystic carcinoma
C. Medullary carcinoma
D. Collecting duct carcinoma Click to register your guess We will reveal the answer in next month’s issue! Do you think you have a good case of the month? Email it to edit@thepathologist.com

Answer to last issue’s Case of the Month… B. Silicosis-associated osteoporosis This disease is an equine osteoporosis associated with pulmonary silicosis (1). Pathognomonic histologic features include:

• large, coalescing foci of osteolysis in the cortical and medullary compartments with disordered remodeling characterized by mosaic arrangement of cement lines
• replacement of compact bone with thin trabecular bone meshwork
• numerous large, hyperactive osteoclasts with supernumerary nuclei and hyperplastic osteoblasts lining many bone surfaces

Bone lesions also often have depletion of hematopoietic bone marrow, congestion, hemorrhage and edema in the intertrabecular stroma. Submitted by Regina Zavodovskaya, PhD Student in the Integrative Pathobiology Graduate Group at the University of California, Davis School of Veterinary Medicine, USA.

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References

1. AM Arens et al., “Osteoporosis associated with pulmonary silicosis in an equine bone fragility syndrome”, Vet Pathol, 48, 593–615 (2011). PMID: 21097716.