18 June 2014 - Case #316
All cases are archived on our website. To view them sorted by case number, diagnosis or category, visit our main Case of the Month page. To subscribe or unsubscribe to Case of the Month or our other email lists, click here.
Thanks to Dr. Elaine Alt, Quest Diagnostics, New Jersey (USA), for contributing this case and discussion.
Advertisement
Case #316
Clinical history:
A 79 year old woman presented with a small gastric antral polyp.
Microscopy images:
What is your diagnosis?
Diagnosis: Gastric plexiform fibromyxoma
Immunostains:
Discussion:
The biopsy shows a mucosa and submucosal multinodular proliferation of cytologically bland spindle cells with a myxoid background. Mitoses were not identified and Ki67 demonstrates a very low proliferation index. The spindle cells are positive for SMA and negative for desmin, CD117, CD34 and polyclonal S100. Prominent arborizing capillaries are highlighted by the CD34 immunostain. These findings are consistent with gastric plexiform fibromyxoma, also known as a plexiform angiomyxoid myofibroblastic tumor (Am J Surg Pathol 2007;31:724, Am J Surg Pathol 2009;33:1624).
The differential diagnosis includes several other predominantly spindle cell lesions. An inflammatory fibroid polyp is usually a single nodule showing more inflammation and often demonstrating a concentric growth of the spindle cells around small blood vessels. In most cases, the spindle cells are CD34 positive. A GIST is often CD117 and CD34 positive and is usually not multinodular and myxoid. Neurofibromas are S100 positive.
Gastric plexiform fibromyxoma is a benign tumor recently added to the WHO classification (IARC: WHO Classification of Tumours of the Digestive System, 4th Edition, 2010). It is considered rare and specific to the stomach. Most are multinoduar masses involving the muscularis propria or submucosa of the antral / prepyloric region, showing microscopically a multinodular proliferation of myofibroblastic cells and arborizing capillaries in a myxoid stroma (World J Gastroenterol 2010;16:2835). They have been seen over a broad age range. Metastases and recurrence following complete excision have not been described.
All cases are archived on our website. To view them sorted by case number, diagnosis or category, visit our main Case of the Month page. To subscribe or unsubscribe to Case of the Month or our other email lists, click here.
Thanks to Dr. Elaine Alt, Quest Diagnostics, New Jersey (USA), for contributing this case and discussion.
TAKE THE RNASCOPE® CHALLENGE
- RNAscope is a pioneering RNA detection technology that allows single-molecules of RNA to be visualized and quantified in situ. The single-molecule sensitivity of RNAscope for detecting RNA while preserving tissue context with single-cell resolution makes it easy to pinpoint which biomarker is expressed in which cells, with the conveniences of a conventional brightfield or standard fluorescence microscope. With RNAscope assays, researchers can detect ANY gene from ANY species in ANY tissue.
- Try RNAscope ISH and we'll credit your antibody expenses towards your purchase. When RNA is present, RNAscope will work with any samples, including FFPE, fixed & fresh frozen tissues.
Website news:
(1) We are pleased to announce 2 special rates for Jobs-Other ads. These are ads for positions other than Pathologist / PhD, which appear on our Jobs-Other page. Through August 2014, the cost to post one of these ads (up to 300 words) is only $325 for up to 6 months. If you post a Job-Other ad within 2 days of posting a Pathologist / PhD ad, the cost is ZERO. Contact us at 248/646-0325 with any questions.
(2) Check out our featured Books of the Month, including WHO Classification of Tumours of Female Reproductive Organs and McGraw-Hill Specialty Board Review Anatomic Pathology.
Visit and follow our Blog to see recent updates to the website.
(1) We are pleased to announce 2 special rates for Jobs-Other ads. These are ads for positions other than Pathologist / PhD, which appear on our Jobs-Other page. Through August 2014, the cost to post one of these ads (up to 300 words) is only $325 for up to 6 months. If you post a Job-Other ad within 2 days of posting a Pathologist / PhD ad, the cost is ZERO. Contact us at 248/646-0325 with any questions.
(2) Check out our featured Books of the Month, including WHO Classification of Tumours of Female Reproductive Organs and McGraw-Hill Specialty Board Review Anatomic Pathology.
Visit and follow our Blog to see recent updates to the website.
Case #316
Clinical history:
A 79 year old woman presented with a small gastric antral polyp.
Microscopy images:
What is your diagnosis?
Click here for diagnosis and discussion:
Diagnosis: Gastric plexiform fibromyxoma
Immunostains:
SMA
CD34
CD117
Desmin
Ki-67
S100
Discussion:
The biopsy shows a mucosa and submucosal multinodular proliferation of cytologically bland spindle cells with a myxoid background. Mitoses were not identified and Ki67 demonstrates a very low proliferation index. The spindle cells are positive for SMA and negative for desmin, CD117, CD34 and polyclonal S100. Prominent arborizing capillaries are highlighted by the CD34 immunostain. These findings are consistent with gastric plexiform fibromyxoma, also known as a plexiform angiomyxoid myofibroblastic tumor (Am J Surg Pathol 2007;31:724, Am J Surg Pathol 2009;33:1624).
The differential diagnosis includes several other predominantly spindle cell lesions. An inflammatory fibroid polyp is usually a single nodule showing more inflammation and often demonstrating a concentric growth of the spindle cells around small blood vessels. In most cases, the spindle cells are CD34 positive. A GIST is often CD117 and CD34 positive and is usually not multinodular and myxoid. Neurofibromas are S100 positive.
Gastric plexiform fibromyxoma is a benign tumor recently added to the WHO classification (IARC: WHO Classification of Tumours of the Digestive System, 4th Edition, 2010). It is considered rare and specific to the stomach. Most are multinoduar masses involving the muscularis propria or submucosa of the antral / prepyloric region, showing microscopically a multinodular proliferation of myofibroblastic cells and arborizing capillaries in a myxoid stroma (World J Gastroenterol 2010;16:2835). They have been seen over a broad age range. Metastases and recurrence following complete excision have not been described.
