of Week Home
12 October 2011 Case of the Week #220
This email is only sent to subscribers. To subscribe or unsubscribe to this or our other email lists, click here.
All cases are archived on our website. To view them sorted by number, diagnosis or category, visit our Home Page and click on the Case of the Week button on the left hand side.
Thanks to Dr. Eddie Fridman, The Chaim Sheba Medical Center, Israel, for contributing this case. To contribute a Case of the Week, follow the guidelines on our Case of the Week page.
CancerTYPE ID is a standardized, objective molecular test based on the differential expression of 92 genes, that classifies tumors by matching the gene expression pattern of a patients tumor tissue to a database of known tumor types and histological subtypes.
CancerTYPE IDs database includes 2,206 tumors from multiple tumor banks, selected to provide broader and deeper representation of the heterogeneity of tumors. The 92-gene assay does not overlap with IHC markers, providing complementary data to standard tumor diagnosis.
CancerTYPE ID uses real-time reverse transcription polymerase chain reaction (RT-PCR). A very low copy number of RNA molecules can be detected, thus reducing the sample tissue required for testing. Testing is conducted and results are generated at bioTheranostics' CAP-accredited, CLIA-certified laboratory.
For more information, click here.
(1) We are looking for more cases of the week (we are down to a two month supply). We are also looking for a reviewer(s) for the Salivary Gland chapter. If interested, please email NatPernick@hotmail.com.
(2) We are looking for pathologists with expertise in the topic to write a 250 word article on "What's New" for these future Feature Pages: Consumable Lab Products (Nov11), Grossing workstations / lab furniture (Dec11), Billing / consulting / management (Jan12), Microscopes / slide imaging (Feb12), for $50 per article. If interested, email Dr. Pernick at email@example.com.
(3) The ASCP published their Fellowship and Job Market survey, click here.
Case of the Week #220
A 37 year old woman had a right renal mass, and underwent a partial nephrectomy.
What is your diagnosis?
Renal angiomyolipoma with predominant smooth muscle component
Immunostains were performed:
Left to right: MNF116 (pan-keratin), HMB45, Desmin
Angiomyolipoma (AML) is a neoplasm composed of blood vessels, smooth muscle and adipose tissue in varying proportions. It derives from the perivascular epithelioid cells, first described in 1991 (Am J Surg Pathol 1991;15:644), but with no known normal cellular counterpart (Arch Pathol Lab Med 2009;133:648). No precursor lesion for PEComas has been described.
PEC related tumors include angiomyolipoma, clear cell sugar tumor, lymphangioleiomyomatosis, and other rare tumors labeled PEC-NOS. These tumors are often perivascular, and have varied histology. The tumor cells have clear to granular, lightly eosinophilic cytoplasm, with small, central nuclei and indistinct nucleoli. There is typically no/mild atypia and no/rare mitotic activity, although exceptions occur. In angiomyolipoma, adipose tissue typically predominates, although cases with mostly smooth muscle, as with this patient, do occur, often in the renal capsule ("capsuloma"). Smooth muscle cells are intimately associated with the vessel walls, and may appear to "spin off" the walls in a radial fashion. The blood vessels are thick walled and tortuous, resembling arteriovenous malformations.
PEComas have a distinctive immunohistochemistry profile, with reactivity for myoid (desmin, smooth muscle actin, calponin) and melanocytic (HMB45, MelanA) markers. Keratins are typically negative, as in this case.
Angiomyolipomas are circumscibed, but not encapsulated. They often become quite large, and can cause life threatening hemorrhage. Although 80% of patients with tuberous sclerosis have angiomyolipomas, most patients with angiomyolipoma do not have tuberous sclerosis (OMIM #191100).
The differential diagnosis of smooth muscle predominant angiomyolipoma includes leiomyoma and leiomyosarcoma. Leiomyoma lacks the characteristic blood vessels and adipose tissue of AML. Leiomyosarcoma typically has prominent nuclear atypia, tumor cell necrosis and mitotic figures.
AML typically has benign behavior, although epithelioid tumors are considered to be malignant with the ability to recur and metastasize. Treatment consists of selective arterial embolization (Eur Urol 2009;55:1155) or excision.
PathologyOutlines.com, Murphy: Tumors of the Kidney Bladder and Related Urinary Structures (AFIP Atlas of Tumor Pathology, Series 4, Vol 1, 2004)
Nat Pernick, M.D., President
30100 Telegraph Road, Suite 408
Bingham Farms, Michigan (USA) 48025
Alternate email: NatPernick@gmail.com