2021-25/ June 21
Contributors: Meenakshi Kamboj

Partial nephrectomy in a 51-year-old female, with a circumscribed solid grey white tumor.


1. What is the correct diagnosis?

a. Leiomyoma

b. Angiomyolipoma

c. Angiomyolipoma with epithelial cysts

d. Mixed epithelial stromal tumor (MEST)

e. Mucinous tubular and spindle cell renal cell carcinoma

c. Angiomyolipoma with epithelial cysts

Microscopic examination showed a predominant spindle cell tumor in interlacing fascicles and whorls with intervening thick walled blood vessels, with spindled cells seen to merge with the outer wall of blood vessels. Embedded within this spindle cell tumor were seen multiple epithelial cyst like spaces (mostly at the periphery of tumor) lined by cuboidal and hobnail cells with surrounding subepithelial compact stroma. No evidence of any high grade atypia/mitosis was seen. The tumor showed focal extension into perinephric fat. Immunohistochemical examination revealed strong expression for CK and PAX8 in the epithelial cyst cells, and the surrounding subepithelial layer expressed HMB45, ER, PR and CD10. The spindled cells were diffusely positive for SMA with patchy positive for HMB45. With this histological and distinct immunoprofile a final diagnosis of Angiomyolipoma with epithelial cysts (AMLEC) was confirmed. The right adnexal mass showed features of torsion ovary with no evidence of any malignancy.

AMLEC is a distinct mesenchymal tumor and rare variant of angiomyolipoma (AML) with few cases reported in literature, characterized by presence of both solid and cystic components as described in above case. It usually presents in the age range of 20 to 76 years. Unlike AML, only one of the 16 cases of AMLEC reported in literature was associated with tuberous sclerosis complex (TSC).[1] The distinct immunohistochemical expression of ER, PR, CD10 and HMB45 in the subepithelial cambium layer suggests the dual differentiation of the stroma into melanocytic and endometrial/Mullerian lineage.[2]
AMLs are benign tumours which are managed conservatively, and complete surgical excision is the treatment of choice.[3] Mixed epithelial and stromal tumour (MEST) forms the closest differential diagnosis. Thus, awareness of this entity may prevent from a misdiagnosis of MEST which unlike AMLEC usually warrants a more aggressive approach.

1. Armah HB, Yin M, Rao UN, Parwani AV. Angiomyolipoma with epithelial cysts (AMLEC): a rare but distinct variant of angiomyolipoma. Diagn Pathol 2007;2:1-5.

2. Filho Jdo E, Meneses de Amorim D, Sweet GM, Rodrigues de Freitas LA, Athanazio PR, Athanazio DA. Renal epithelioid angiomyolipoma with epithelial cysts: demonstration of Melan A and HMB45 positivity in the cystic epithelial lining. Ann Diagn Pathol 2012;16:397-401. doi: 10.1016/j.anndiagpath.2011.03.004.

3. LeRoy MA, Rao P. Angiomyolipoma with epithelial cysts. Arch Pathol Lab Med. 2016;140:594-7.

Meenakshi Kamboj
Rajiv Gandhi Cancer Institute and Research Centre
Delhi, India


kidney, Angiomyolipoma, epithelial cysts, HMB45