Case Presentation - Summer, 2011

Benign Inflammatory Myofibroblastic Tumor

Patient History: Female, age 21

Specimen type: FNA-Right Breast 2:00

Cytologic diagnosis: Atypical, suggestive of a spindle cell lesion

Biopsy diagnosis: Biopsy-Benign Inflammatory Myofibroblastic Tumor

Inflammatory Myofibroblastic Tumor (IMT) is a benign tumor that has been found in most organs, but most commonly occurs in the lung. It is very rarely found in the breast. IMT is known by many names including, but not limited to Benign Inflammatory Myofibroblastic Tumor, Inflammatory Pseudotumor, Plasma Cell Granuloma, Inflammatory Fibrosarcoma and Fibroxanthoma. Its etiology is not clear. Studies have shown the presence of Human Herpes Virus-8 present in a small number of cases as well as Epstein - Barr virus. Cytogenetic alterations involving a chromosomal translocation of 2p23 leading to an immunoexpression of the protein anaplastic lymphoma kinase (ALK) have been noted in some cases leading some to believe that this tumor is a true neoplasm rather than of infectious etiology. Another area of interest has been the possible overproduction of the cytokines IL-1 and IL-6 which would lead to the proliferation of fibroblasts.

Clinical Features:
This lesion may be asymptomatic and is often discovered on screening mammography. Typical presentation is a firm, mobile, non-tender mass. Skin retraction may be present. Splenomegaly and fever of unknown origin may also be seen. It is more common in women and can clinically mimic malignancy. A preoperative ultrasound guided biopsy is essential in avoiding unnecessary mastectomy

Treatment and Prognosis:
Complete surgical excision is the standard of care for the treatment of this tumor. There is a chance of local recurrence and re-excision may be necessary. When complete excision is performed, the prognosis is favorable.

An FNA of IMT yields a mildly cellular specimen consisting of benign appearing spindle cells with both acute and chronic inflammatory cells. Benign ductal cells and connective tissue may also be present.

Differential Diagnosis:
Low grade spindle cell lesions with inflammatory cells need to be distinguished from IMT. Immunoperoxidase staining for smooth muscle actin, vimentin and cytokeratins can be helpful as well as the lack of cellular pleomorphism and true nuclear atypia.

  1. Atkinson, B., Silverman, J. Atlas of Difficult Diagnoses in Cytopathology. 1998: 508.
  2. Cibas, E., Ducatman, B. Cytology Diagnostic Principles and Clinical Correlates Second Edition. 2003: 77.
  3. Koss, L., Woyke,S., Olszewski, W. Aspiration Biopsy Cytologic Interpretation and Histologic Bases Second Edition. 1992: 506-509.
  4. Sidawy, M., Ali, S. Fine Needle Aspiration Cytology A volume in the series Foundations in Diagnostic Pathology. 2007: 231-232.
  5. Ali, S., Parwani, A., Breast Cytopathology, Essentials in Cytopathology Series. 2007: 51-52.
  6. Kim, S., Moon, W., Kim, J., Cho, M., Chang, C.: Inflammatory Pseudotumor of the Breast: A Case Report with Imaging Findings. Korean Journal of Radiology, 2009 Volume 10(5) 515-518
  8. Park, S., Kim, H., Shin, H., Gong, G., Inflammatory Pseudotumor (Myoblastic Tumor) of the Breast: a Case Report and Review of the Literature. Journal of Clinical Ultrasound, 2009 Volume 38 Issue 1.