Monotypic epithelioid angiomyolipoma of the kidney: a case report

Hepatic epithelioid angiomyolipoma: an analysis of two cases

AIM: To investigate the clinicopathologic characteristics of hepatic epithelioid angiomyolipoma (EAML).

METHODS: Two cases of hepatic EAML treated at General Hospital of Wuhan Iron and Steel Corporation from 2007 to 2009 were analyzed in this study. The clinicopathologic and immunohistochemical characteristics of the disease were described and the related literature was reviewed.

RESULTS: Both patients are female. Both cases of hepatic EAML had clear boundaries. The tumors were characterized by diffused epithelioid neoplastic cells. The epithelioid cells were round with eosinophilic or clear cytoplasm, and few neoplastic cells showed cellular atypia. Immunohistochemically, the neoplastic cells were diffusely positive for HMB45, Melan-A and SMA.

CONCLUSION: Hepatic EAML is a rare mesenchymal neoplasm. The diagnosis and differentiatial diagnosis of EAML rely mainly on histopathology and immunohistochemistry.

Renal epithelioid angiomyolipoma: a study of six cases and a meta-analytic study. Development of criteria for screening the entity with prognostic significance

AIMS

Renal epithelioid angiomyolipoma (EAML) is only described in case reports or in multi-institutional small series. The aim was to report cases seen at our institution and to perform a meta-analysis based on a literature review.

METHODS AND RESULTS

Six EAML cases seen at our institution were reviewed and a meta-analysis performed using cases retrieved from a literature review. There were a total of 69 cases for review. The male:female ratio was 1:3. In the absence of areas of typical AML, useful features in distinguishing EAML from epithelial renal neoplasms include: extreme degree of cytological atypia, histiocytoid appearance, presence of melanocytic pigments, solid architecture with the absence of frequent areas of alveolar pattern, tubulo-papillary formation and scarring. A fatal outcome, distant or lymph node metastasis, venous invasion and local recurrence were considered as adverse events and occurred in 40% of cases over a period of follow-up of 3-60 months (mean 22.5 +/- 18 months). Tumours with an unfavourable outcome showing marked cytological atypia and extensive tumour necrosis were larger (135 +/- 43 mm) than those with a favourable outcome (79 +/- 50 mm) (P < 0.002), and predominantly occurred in men.

CONCLUSIONS

Renal neoplasms with certain unusual features should be investigated immunohistochemically to rule out the possibility of EAML. The frequency of adverse outcome is lower in EAML than in renal cell carcinoma.

Renal angiomyolipoma: clinicopathologic study of 194 cases with emphasis on the epithelioid histology and tuberous sclerosis association

The majority of renal angiomyolipoma (AML) is sporadic and occasionally it occurs as part of tuberous sclerosis complex (TSC). Epithelioid AML (EAML), an uncommon variant, is considered potentially malignant based on anecdotal case reports. The prognostic significance of epithelioid component in an otherwise typical AML is uncertain. We studied 194 AMLs for the clinicopathologic features of epithelioid and TSC-associated AMLs. Epithelioid component was present in 15 cases (7.7%) with an average amount of 51% (range: 10% to 100%). Histologically, the epithelioid tumor cells were categorized into small, intermediate, and large cell type based on the cell size. Worrisome histologic features were seen in many EAMLs, including coagulative tumor necrosis in 27% (4/15), nuclear atypia in 93% (14/15), mitosis in 47% (7/15), and atypical mitosis in 1 case. All 15 EAML patients had a mean follow-up time of 5.1 years and none had local recurrence or distant metastasis. Sixteen (8.2%) AMLs occurred in patients with definitive TSC. Three histologic features, namely microscopic AML foci, epithelioid component, and epithelial cysts, were present in 10 (62.5%), 4 (25%), and 44% (7/16), respectively, of TSC-associated AMLs, compared with 11 (6.2%), 11 (6.2%), and 6 (3.4%), respectively, in non-TSC-associated AMLs (P value all <0.01). In summary, all 15 cases of EAMLs in our study had benign clinical outcomes despite adverse pathologic features. Epithelioid component, epithelial cysts, and microscopic AML foci are strongly associated with TSC and the presence of all 3 features should raise strong suspicion for TSC.

[Epithelioid angiomyolipoma of the kidney]

A 37-year-old female was referred to our department for a renal mass which was incidentally found during a medical check-up. She had no history of tuberous sclerosis. Computed tomography and magnetic resonance imaging showed a 1.5-cm enhancing mass at the lower pole of the left kidney. An open partial nephrectomy was performed for a pre-operative diagnosis of renal cell carcinoma. Pathological examination revealed sheets of large polygonal epithelioid cells that showed positive immunostaining for HMB-45, which confirmed the diagnosis of an epithelioid angiomyolipoma. The patient remained free of recurrent or metastatic disease at 3 months of follow-up. Epithelioid angiomyolipoma is a recently identified variant of angiomyolipoma, which is sometimes associated with aggressive clinical behavior including local recurrence and metastasis. We present this case and review the literature concerning this unusual disorder.