Pathology – Research and Practice 209 (2013) 605–608 Contents lists available at ScienceDirect Pathology – Research and Practice j ourna l h om epage: www.elsevier.com/locate/prp Teaching case Tumor-to-tumor metastasis (TTM) of breast carcinoma within a solitary renal angiomyolipoma: A case report Milon Amin * , Lisa Radkay, Liron Pantanowitz, Jeffrey Fine, Anil Parwani Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, PA, United States a r t i c l e i n f o Article history: Received 30 March 2013 Received in revised form 1 June 2013 Accepted 25 June 2013 Keywords: Angiomyolipoma Collision Renal Carcinoma Breast a b s t r a c t Angiomyolipomas of the kidney have been known to harbor malignant neoplasms including renal cell carcinoma. We report a case of a tumor-to-tumor metastasis (TTM) involving metastatic breast carcinoma and angiomyolipoma. The patient was a 67-year-old female with a history of invasive ductal carcinoma of the breast. Follow-up positron emission tomography 9 years later revealed a left renal mass, suspicious for a primary renal neoplasm, as well as a suspicious subpectoral lymph node. An ultrasound-guided needle biopsy of the lymph node demonstrated metastatic breast carcinoma. The patient underwent a left radical nephrectomy. Pathologic examination demonstrated an ill-defined 2 cm estrogen receptor (ER)- positive metastatic breast carcinoma within a 6 cm angiomyolipoma. To our knowledge, this is the first reported case of metastatic breast carcinoma to a solitary renal angiomyolipoma. This case highlights the importance of a patient’s prior history of malignancy, as well as appropriate sampling of renal neoplasms. © 2013 Elsevier GmbH. All rights reserved. Introduction “Tumor-to-tumor metastasis” (TTM) is a term describing the presence of two histologically distinct tumors at one location, each with different morphologic and immunophenotypic features, as well as differing primary sites of origin [3]. Berent initially documented this phenomenon in 1902 [2]. Although rare, TTMs involving angiomyolipomas in the kidney have been reported, with recent examples including metastatic adenocarcinoma of the lung and neuroendocrine carcinoma of the pancreas [12]. Given that an angiomyolipoma typically follows a benign clinical course, its dis- tinction from malignant neoplasia, both primary and metastatic, is essential for proper management. We report a case of ductal carcinoma of the breast metastatic to a solitary renal angiomy- olipoma. Clinical history A 67-year-old female with a history of invasive ductal carci- noma of the breast, status post right mastectomy in 1992 and left lumpectomy in 2001, underwent routine post-surgical follow-up. Information on hormone receptor and HER2/neu status was not * Corresponding author at: UPMC Shadyside, Department of Pathology, 5230 Cen- tre Avenue, West Wing, Basement Suite WG02.3, Pittsburgh, PA 15232, United States. Tel.: +1 412 623 3002. E-mail addresses: milon.amin@outlook.com, milon@hucm.net (M. Amin). available. Position emission tomography/computed tomography (PET-CT) in 2011 showed a new suspicious enhancing right subpectoral node, 1.8 cm in greatest dimension, with increased fluorodeoxyglucose (FDG) uptake. Also identified was a left mid-to- lower pole renal mass, 4.1 cm in greatest dimension, with increased FDG uptake suggestive of renal or transitional cell carcinoma. There was dilatation of the renal collecting system, but no enlarged or FDG-avid lymph nodes in the abdomen or pelvis. Urine cytology was performed and was negative. The patient underwent a radical nephrectomy and needle biopsy of the subpectoral lymph node. Materials and methods Specimens were fixed in 10% formalin and processed for histological examination using conventional methods. Histologic sections were stained with hematoxylin and eosin (H&E). Immuno- histochemical studies (pankeratin, cytokeratin 7 (CK7), E-cadherin, p120 catenin, mammaglobin, gross cystic disease fluid protein (GCDFP-15), estrogen receptor (ER), progesterone receptor (PR), thyroid transcription factor-1 (TTF-1), cytokeratin 20 (CK20), CD10, P504S (alpha-methylacyl CoA racemase), CDX-2 and PAX-8, Ven- tana, Oro Valley, AZ) and fluorescence in situ hybridization (FISH) studies (HER2/neu expression, PathVysion Her-2 DNA kit, Abbott Molecular, Des Plains, IL) were also performed using formalin-fixed, paraffin-embedded sections. Avidin–biotin peroxidase complex and peroxidase–antiperoxidase techniques were employed with appropriate positive and negative controls. 0344-0338/$ – see front matter © 2013 Elsevier GmbH. All rights reserved. http://dx.doi.org/10.1016/j.prp.2013.06.011