Malakoplakia is a characteristic inflammatory condition, which is usually seen in the urogenital tract, and less frequently in the gastrointestinal tract. We present a case of colonic malakoplakia in an immunocompromised patient. A 55-year-old female visited the outpatient clinic for routine cancer surveillance. Her past medical history was significant for kidney transplantation 11 years ago, and she had been taking immunosuppressants. A colonoscopy revealed several depressed flat lesions and elevated polyps, which were 0.3 to 0.4 cm in size and accompanied by whitish exudates. A biopsy revealed an infiltration of histiocytes with ample granular eosinophilic cytoplasm, with some lymphocytes and plasma cells. Many histiocytes had the characteristic morphology, described as Michaelis-Gutmann bodies: one or several round basophilic structures of approximately 1 to 10 µm in size with some being laminated, some appearing homogeneous, and others having a dense central core with a targetoid appearance. These Michaelis-Gutmann bodies were positively stained on von Kossa stain, and were diagnostic for malakoplakia.

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Citations to this article as recorded by  

• Malakoplakia in kidney transplant recipients: Three case reports
  Prathap Kumar Simhadri, Renish Contractor, Deepak Chandramohan, Matthew McGee, Udit Nangia, Mohammad Atari, Syed Bushra, Sanjana Kapoor, Ramya Krishna Velagapudi, Pradeep K Vaitla
  World Journal of Nephrology.2025;[Epub]     CrossRef
• Caecal malakoplakia: a rare mimic of malignancy
  Jeffrey Li Voon Chong, Noor Ali
  BMJ Case Reports.2024; 17(1): e257130.     CrossRef
• A Surgical Challenge Generated by Colonic Malakoplakia in Disguise as a Locally Advanced Colonic Malignancy—A Case Report
  Cristina Șerban, Alexandra Toma, Dragoș Cristian Voicu, Constantin Popazu, Dorel Firescu, George Țocu, Raul Mihailov, Laura Rebegea
  Medicina.2023; 59(1): 156.     CrossRef
• Colonic malakoplakia in a cardiac transplant recipient: A case report
  Sadiya Shafijan
  Indian Journal of Pathology and Microbiology.2020; 63(2): 322.     CrossRef
• Immunosuppressive drugs and the gastrointestinal tract in renal transplant patients
  Merel M. Tielemans, Gerben A.J. van Boekel, Teun van Gelder, Eric T. Tjwa, Luuk B. Hilbrands
  Transplantation Reviews.2019; 33(2): 55.     CrossRef
• Malakoplakia of the colon following renal transplantation in a 73 year old woman: report of a case presenting as intestinal perforation
  Andrew Mitchell, Alexandre Dugas
  Diagnostic Pathology.2019;[Epub]     CrossRef
• Colonic malakoplakia in a liver transplant recipient: A case report
  Rana Ajabnoor, Mohammad Mawardi, Abdulmonem Almutawa
  Human Pathology: Case Reports.2019; 18: 200323.     CrossRef
• Malakoplakia after kidney transplantation: Case report and literature review
  John Fredy Nieto‐Ríos, Isabel Ramírez, Mónica Zuluaga‐Quintero, Lina María Serna‐Higuita, Federico Gaviria‐Gil, Alejandro Velez‐Hoyos
  Transplant Infectious Disease.2017;[Epub]     CrossRef
• Megalocytic Interstitial Nephritis Following Acute Pyelonephritis with Escherichia coli Bacteremia: A Case Report
  Hee Jin Kwon, Kwai Han Yoo, In Young Kim, Seulkee Lee, Hye Ryoun Jang, Ghee Young Kwon
  Journal of Korean Medical Science.2015; 30(1): 110.     CrossRef

Metaplastic thymoma (MT), accepted in the World Health Organization 2004 scheme, is a circumscribed tumor of the thymus exhibiting biphasic morphology. We herein describe the clinicopathologic features of four MTs and the differential diagnoses of this unusual tumor. There were three women and one man with mean age of 49.5 years. The patients were found to have mediastinal masses, and underwent surgical excision. One exhibited symptoms of myasthenia gravis, and the serum titer for anti-acetylcholine receptor antibody was positive. Grossly, the tumors were encapsulated, and showed vaguely multinodular, solid, tan-white to yellow cut surfaces. Histologically, they comprised epithelial islands intertwining with bundles of delicate spindle cells. The patients remained well after surgical excision at 5-55 months. Because of the distinctive histological appearance and benign clinical course, MT should be distinguished from other more aggressive mediastinal neoplasms displaying biphasic feature.

Citations

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• A Rare Case of Metaplastic Thymoma Presenting With Myasthenia Gravis
  Ilianne Vega Prado, John Shymansky, Anisha Apte, Keith Mortman, Henry J. Kaminski, Stephanie Barak
  International Journal of Surgical Pathology.2024; 32(1): 155.     CrossRef
• Thymic epithelial tumours: histopathological classification and differential diagnosis
  Jan von der Thüsen
  Histopathology.2024; 84(1): 196.     CrossRef
• Epigenetics of Thymic Epithelial Tumors
  Vanessa Nicolì, Fabio Coppedè
  Cancers.2023; 15(2): 360.     CrossRef
• Expanding the Clinicopathologic Spectrum of YAP1::MAML2–Rearranged Thymic Neoplasm
  Eric Eunshik Kim, Ye Yoon Suh, Sang Won Lee, Jeong Mo Bae, Kyoungbun Lee, Sungyoung Lee, Hongseok Yun, Kyeong Cheon Jung, Jiwon Koh
  Modern Pathology.2023; 36(2): 100048.     CrossRef
• Significance of YAP1–MAML2 rearrangement and GTF2I mutation in the diagnosis and differential diagnosis of metaplastic thymoma
  Minghao Wang, Hongtao Xu, Qiang Han, Liang Wang
  Annals of Medicine.2023;[Epub]     CrossRef
• Loss of YAP1 C‐terminus expression as an ancillary marker for metaplastic thymoma: a potential pitfall in detecting YAP1::MAML2 gene rearrangement
  Xuan Wang, Lei‐lei Liu, Qing Li, Qiu‐yuan Xia, Rui Li, Sheng‐bing Ye, Ru‐song Zhang, Ru Fang, Hui Chen, Nan Wu, Qiu Rao
  Histopathology.2023; 83(5): 798.     CrossRef
• A Case of Metaplastic Thymoma
  Ryoichi TAKENAKA, Kenji NEZU, Daijiro TAKEMOTO, Tatsuya HAYASHI, Hisato YAMAMOTO, Shoichi MATSUKAGE
  Nihon Rinsho Geka Gakkai Zasshi (Journal of Japan Surgical Association).2023; 84(4): 538.     CrossRef
• Malignant Transformation of Metaplastic Thymoma into High-Grade Sarcomatoid Carcinoma: A Case Report
  Zheng Hua Piao, Jin Ping Chen, Hai Ren Chen, Xin Cheng Zhou
  International Journal of Surgical Pathology.2022; 30(5): 564.     CrossRef
• YAP1-MAML2 Fusion as a Diagnostic Biomarker for Metaplastic Thymoma
  Jikai Zhao, Ruiying Zhao, Chan Xiang, Jinchen Shao, Lianying Guo, Yuchen Han
  Frontiers in Oncology.2021;[Epub]     CrossRef
• Metaplastic thymoma: a distinctive thymic neoplasm characterized by YAP1-MAML2 gene fusions
  Marina Vivero, Phani Davineni, Valentina Nardi, John K.C. Chan, Lynette M. Sholl
  Modern Pathology.2020; 33(4): 560.     CrossRef
• Metaplastic thymoma: Report of two cases
  Yoshikazu Shinohara, Mariko Tanaka, Kentaro Kitano, Kazuhiro Nagayama, Masaaki Sato, Jun Nakajima
  The Journal of the Japanese Association for Chest Surgery.2020; 34(7): 733.     CrossRef
• Type AB thymoma is not a mixed tumor of type A and type B thymomas, but a distinct type of thymoma
  Yukari Miki, Kana Hamada, Tadashi Yoshino, Katsuya Miyatani, Kiyoshi Takahashi
  Virchows Archiv.2014; 464(6): 725.     CrossRef
• Potential Role of Adjuvant Radiation Therapy in Cervical Thymic Neoplasm Involving Thyroid Gland or Neck
  Jae Myoung Noh, Sang Yun Ha, Yong Chan Ahn, Dongryul Oh, Seung Won Seol, Young Lyun Oh, Joungho Han
  Cancer Research and Treatment.2014; 47(3): 436.     CrossRef
• A Case of Metaplastic Thymoma
  Eiji MIYAHARA, Tomoko ITAGAKI, Masaki KUWAHARA, Akira KAMEDA, Yoshihiro MIYATA, Kazuhiro SENTANI, Wataru YASUI
  Nihon Rinsho Geka Gakkai Zasshi (Journal of Japan Surgical Association).2014; 75(2): 360.     CrossRef