Cystic Neoplasms of Kidney in Adults

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Cystic Neoplasms of Kidney in Adults

• L. Priya Kunju, M.D.
• Assistant Professor
• Department of Pathology
• The University of Michigan

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Case 11Patient history

• 47 Y Male patient with a complex cystic renal
  mass noted on CT who underwent partial
  nephrectomy
• A 2 cm complex cystic renal mass was noted

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Diagnosis Angiomyolipoma with Epithelial Cysts
(AMLEC)
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Angiomyolipoma

• Sporadic or in association with Tuberous
  Sclerosis
• Arise from perivascular epitheliod cells (HMB-45
  positive)
• Solid tumors, well demarcated from adjacent
  kidney
• Composed of varying mixtures of blood-vessels,
  smooth muscle and fat

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• Angiomyoplioma with Epithelial Cysts
• Gross
• Complex cystic mass
• Microscopic features
• Multiple cysts lined by epithelium columnar,
  cuboidal. Abundant eosinophilic cytoplasm
• with hob-nail appearance

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• Angiomyoplioma with Epithelial Cysts
• Microscopic features
• Sub-epithelial cambium-like condensation of
  stromal cells.
• Stroma with prominent capillary vascularity.

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• AMLEC
• Microscopic features
• Smooth muscle arranged in poorly formed
  fascicles
• Intimately association with thick-walled blood
  vessels
• Entrapped renal tubules

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AMLEC Immunohistochemistry HMB-45, Melan-A
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AMLEC Immunohistochemistry HMB-45, Melan-A
ER/PR Desmin/SMA
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Cystic Renal Mass
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Cystic Neoplasms of KidneysDifferential Diagnosis

• Renal Cell Carcinoma
• Multilocular cystic RCC
• Tubulocystic RCC (GU Break-out session)
• Mixed epithelial and stromal tumor
• Cystic nephroma (multilocular cyst)
• Angiomyolipoma with epithelial cysts
• Cystic partially differentiated nephroblastoma

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Multilocular Cystic Renal Cell Carcinoma
Expansile cystic mass with fibrous
pseudocapsule Composed entirely of cysts and
septa NO solid expansile nodules
Cysts lined by epithelial cells with low
Fuhrman grade nuclei Fibrous septa that
contain clusters of epithelial cells
with clear cytoplasm
Uncommon tumor of adults Male predominance
(31) No documented progression/recurrence
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Multilocular Cystic Renal Cell CarcinomaCritical
Issues

• Distinct subtype of conventional clear cell RCC
• Volume of carcinoma cells may be small.
• Potential mis-diagnosis as a benign multilocular
  cyst
• Sampling is key, IHC ( CK, EMA ) useful
• Reporting as Clear cell type RCC, with
  prominent cystic changes
• Prognostic Implications
• Multiloculated Cystic RCC has excellent
  prognosis

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Mixed Epithelial Stromal Tumor of Kidney

• Multiple terminology cystic hamartoma of renal
  pelvis, mesoblastic nephroma of adults
• Strong female predominance, often perimenopausal
• No recurrence reported
• GROSS
• Variable amounts of solid areas and multiple
  cysts
• Solid areas may be extensive
• Septa of cysts thick

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Mixed Epithelial Stromal Tumor of Kidney

• Variably sized cysts and tubules
• Simple microcysts with abundant stroma to densely
  packed microcysts/complex branching tubules
• Columnar/cuboidal epithelium with
  clear/pale/vaccuolated/
• eosinophilic cytoplasm
• Stroma composed of variably cellular spindle
  cells

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• Mixed Epithelial Stromal
• Tumor of Kidney
• Complex tumors with large cysts
• Cysts may be lined by hob-nail cells
• Smooth muscle bundles in stroma
• Urothelium (hyperplastic) may line cysts

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• Mixed Epithelial Stromal
• Tumor of Kidney
• Stroma composed of variably cellular spindle
  cells
• Myxoid stroma and smooth muscle bundles may be
  prominent
• Blood vessels with thick walls may be present
• NO cytologic atypia and/or mitosis

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Mixed Epithelial Stromal Tumor of
Kidney Immunohistochemistry Desmin SMA ER/PR
HMB-45 Negative
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Cystic Nephroma(Multilocular Benign Cyst)

• Benign neoplasm occurring predominantly in
  adults
• Strong female predominance (81)
• Usually found incidentally, rarely present with
  pain, palpable mass
• Entirely cystic mass,
• NO solid nodules
• Excision is curative

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Cystic Nephroma

• Mass composed exclusively of cysts covered by
  fibrous pseudocapsule
• Cysts lined by flattened cuboidal or hobnail
  epithelium
• Nuclei are low-grade with no prominent nucleoli
• No solid nodules
• No clusters of clear epithelial cells

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Cystic Nephroma

• Septa show myxoid to collagenous stroma
• Cellular spindle cell stroma resembling ovarian
  stroma may be seen (Strongly positive for ER and
  PR)
• Septa may contain entrapped renal tubules
• No smooth or skeletal muscle

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Are Cystic Nephromas and Mixed Epithelial
Stromal Tumors of Kidney A Single Entity?
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Are Cystic Nephromas and Mixed Epithelial
Stromal tumors of Kidney A Single Entity?

• Points in Favor
• Overlapping gross and microscopic features
• Overlapping immunohistochemical features
• Both tumors are predominant in females

• Points Against
• Similar gross and microscopic areas may be seen
  in CPDN, MCRCC
• Some (? crucial) differences
• Several unrelated tumors (MA, Mucinous tubular
  spindle RCC, AML) are predominant in females

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Immunohistochemical Profile
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Cystic Neoplasms of KidneysTake-Home Message

• Angiomyolipoma with epithelial cysts (AMLEC)
  should be included in the differential diagnosis
  of adult cystic renal neoplasms.
• Differential diagnosis of adult cystic renal
  neoplams also include multilocular cystic RCC,
  tubulocystic RCC, cystic nephroma (CN) and mixed
  epithelial stromal tumor of kidney (MEST)
• Cystic partially differentiated nephroblastoma
  (CPDN) are cystic renal neoplasms common in
  children (unusual after 2Y),
• - Blastemal cells and undifferentiated
  mesenchyma elements
• - Commonly shows skeletal muscle in septa

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Cystic Neoplasms of KidneysTake- Home Message

• AMLEC and MEST may have overlapping morphologic
  features, however the most distinctive
  immunohistochemical feature distinguishing the
  two entities is the fact that MEST, unlike AMLEC,
  does not label with melanocytic markers (HMB-45
  and/or Melan A)

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Thank You