Renal Cystic Lesion in Elderly Man

Specimen Type:

Kidney

History:

A 70-year-old male with a renal mass underwent partial nephrectomy. Grossly, the specimen is a spongy, brown soft tissue and at section, an ill defined white, cystic nodule appeared measuring 1.5 cm in greater diameter. Representative cross-sections were submitted.

Pathologic Features:

Sections revealed a well-circumscribed tumor (Fig.1) characterized by tubules of markedly variable size (Fig.2) that were lined by low cuboidal and hobnail epithelial cells with prominent nucleoli and modest to abundant eosinophilic cytoplasm. The tubules were separated by fibrous septa of variable thickness (Fig.3-4).

Differential Diagnosis:

  • Segmental cystic disease
  • Mucinous tubular and spindle cell carcinoma (Fig.1.5)
  • Wilms’ tumor and Cystic Partially Differentiated Nephroblastoma (Fig.1.6-1.7)
  • Cystic nephroma (Fig.1.8)
  • Cystic multilocular clear cell renal cell carcinoma
  • Tubulocystic carcinoma (Fig.1.9)
  • Carcinoma of the collecting ducts of Bellini (Fig.1.10)
  • Papillary renal cell carcinoma (Fig.1.11)
  • Congenital mesoblastic nephroma (Fig.1.12)

Segmental cystic disease: Unilateral and segmental form of cystic disease histologically resembles adult polycystic kidney disease but lacks the progression, extrarenal complications, and familial nature. An early stage of adult polycystic kidney disease is often entertained because early on one kidney may be more severely affected. Careful imaging of the opposite kidney and inquiry into family history is required.

Diagnosis:

Key Features:

  • Rare and distinctive entity recently recognized
  • Occurs in adults and elderly patients
  • Well-circumscribed; grossly cystic, may have “bubble wrap” appearance at cut surface
  • Low power: Tubules of markedly variable size separated by delicate or fibrous septa (“spiderweb” architecture)
  • High power: Same tubules lined by low cuboidal or hobnail epithelial cells with prominent nucleoli
  • Necrosis and mitotic activity are virtually absent
  • Histogenesis remains uncertain: proximal tubule or collecting duct; the tumor seen here is focally positive for 34βE12 (collecting duct marker) (Fig.1.13)
  • Indolent biologic activity; potential for metastasis being less than 10%
  • Entity that needs to be studied and characterized more fully

References:

  1. MacLennan GT, Bostwick DG. Tubulocystic carcinoma, mucinous tubular and spindle cell carcinoma, and other recently described rare renal tumors. Clin Lab Med. 2005;25:393-416.
  2. Radhakrishnan A, MacLennan GT, Hennigar RA, et al. Ultrastructural and immunohistochemical appraisal of tubulocysytic carcinoma of the kidney: histogenetic and diagnostic implications. Mod Pathol 2005;18:160A.
  3. Radhakrishnan A, MacLennan GT, Hennigar RA, et al. Ultrastructural and immunohistochemical appraisal of tubulocysytic carcinoma of the kidney: histogenetic and diagnostic implications. Mod Pathol 2005;18:160A.
  4. MacLennan GT, Farrow GM, Bostwick DG. Low-grade collecting duct carcinoma of the kidney: report of 13 cases of low-grade mucinous tubulocystic renal carcinoma of possible collecting duct origin. Urology. 1997;50(5):679-84.