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17 December 2014 - Case #337

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Thanks to Dr. Ankur Sangoi, El Camino Hospital, California (USA), for contributing this case.




Establishing the spatial / cellular context of gene expression and validating NGS gene discoveries using RNA in situ Hybridization

Pronin et al. used RNA-seq to sequence the entire transcriptome of the mouse cornea and identified ~10,000 actively transcribed genes. Among them there were 194 GPCRs, of which 96 were putative olfactory receptors (Olfrs). They went on to validate the 20 Olfrs by RT-PCR and RNA in situ hybridization (ISH) via RNAscope® technology.

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  • Validate RNA-Seq results
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  • Visualize RNA targets in the full context of tissue architecture


    Expression of Olfr558 in vessels of the choroid and retina (Pronin et al., 2014). In situ hybridization of the mouse choroid slices with Olfr558 probe (red dots). Nuclei staining is DAPI (blue dots).

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Case #337

Clinical history:
A 51 year old diabetic woman presented with a breast mass. A lumpectomy was performed.

Microscopic images:



What is your diagnosis?

Click here for diagnosis and discussion:


Diagnosis: Lymphocytic mastitis / diabetic mastopathy

Discussion:
Lymphocytic mastitis, also called diabetic mastopathy or sclerosing lymphocytic lobulitis, is an uncommon finding typically associated with type I diabetes or other autoimmune diseases but also found in type II diabetes or patients without diabetes (Diabetes Care 2002;25:121, Hum Pathol 1992;23:780, Am J Clin Pathol 2000;113:541).

Clinically, patients may present with a palpable mass, often bilateral. The specimen has a gray-white, smooth cut surface. Microscopically, there is an ill defined lesion of dense intralobular, perilobular and perivascular lymphocytes, with possible lymphoid follicles and germinal centers. There is associated lobular atrophy and sclerosis, histiocytes and fibroblasts (Stanford University: Surgical Pathology Criteria [Accessed 27 December 2023]). The lymphocytes are polyclonal, and predominantly B cells (Mod Pathol 2003;16:223). Variable features include vascular calcifications, epithelioid fibroblasts which may resemble carcinoma, fat necrosis and noncaseating granulomas (Pathol Int 2012;62:660, Mod Pathol 1994;7:49, Am J Surg Pathol 2006;30:1330).

The histologic differential diagnosis includes:
Although lymphocytic mastitis is benign and not associated with malignancy, up to 30% recur (Am J Clin Pathol 2000;113:541). Recognition is important to prevent unnecessary repeat biopsies.


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