How To Diagnose Benign Bone Tumors In The Lower Extremity

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Continuing Education Course #119 — May 2004

I am very pleased to introduce the latest article, “How To Diagnose Benign Bone Tumors In The Lower Extremity,” in our CE series. This series, brought to you by HMP Communications, consists of regular CE activities that qualify for one continuing education contact hour (.1 CEU). Readers will not be required to pay a processing fee for this course.

Benign bone tumors in the lower extremity range from the relatively common Dupuytren’s exostosis to enchondromas and giant cell tumors. Bradley Bakotic, DPM, DO, provides a thorough review of various benign bone tumors that one may see in the feet. He offers key insights on the clinical presentation of these lesions and discusses what diagnostic signs clinicians should look for on radiographs.

At the end of this article, you’ll find a nine-question exam. Please mark your responses on the enclosed postcard and return it to HMP Communications. This course will be posted on Podiatry Today’s Web site (www.podiatrytoday.com) roughly one month after the publication date. I hope this CE series contributes to your clinical skills.

Sincerely,

Jeff A. Hall
Editor-In-Chief
Podiatry Today

INSTRUCTIONS: Physicians may receive one continuing education contact hour (.1 CEU) by reading the article on pg. 67 and successfully answering the questions on pg. 74. Use the enclosed postcard to submit your answers or log on to www.podiatrytoday.com and respond electronically.
ACCREDITATION: HMP Communications, LLC is approved by the Council on Podiatric Medical Education as a sponsor of continuing education in podiatric medicine.
DESIGNATION: This activity is approved for 1 continuing education contact hour or .1 CEU.
DISCLOSURE POLICY: All faculty participating in Continuing Education programs sponsored by HMP Communications, LLC are expected to disclose to the audience any real or apparent conflicts of interest related to the content of their presentation.
DISCLOSURE STATEMENTS: Dr. Bakotic has disclosed that he has no significant financial relationship with any organization that could be perceived as a real or apparent conflict of interest in the context of the subject of his presentation.
GRADING: Answers to the CE exam will be graded by HMP Communications, LLC. Within 60 days, you will be advised that you have passed or failed the exam. A score of 70 percent or above will comprise a passing grade. A certificate will be awarded to participants who successfully complete the exam.
TARGET AUDIENCE: Podiatrists.
RELEASE DATE: May 2004.
EXPIRATION DATE: May 31, 2005.
LEARNING OBJECTIVES: At the conclusion of this activity, participants should be able to:
• differentiate between benign bone tumors based on clinical characteristics and diagnostic imaging;
• discuss the frequency, etiology and clinical progression of Dupuytren’s exostosis;
• describe the radiologic features of aneurysmal bone cysts and chondroblastomas; and
• discuss the key clinical characteristics of giant cell tumors and appropriate staging of these tumors.

Sponsored by HMP Communications, LLC.

In this plain film radiograph, one can see a Dupuytren’s exostosis attached to the distal phalanx of a lesser digit by a narrow base.
In this plain film radiograph, one can see an aneurysmal bone cyst causing a lytic expansion of the fourth metatarsal.
This high power hematoxylin and eosin-stained section demonstrates a lobule of plasmacytoid chondroblasts.
This high power hematoxylin and eosin-stained section demonstrates atypical chondrocytes in bizarre parosteal osteochondromatous proliferation (Nora’s lesion).
This plain film radiograph offers a mortise view of chondroblastoma within the subchondral talus.
74
Author(s): 
By Bradley W. Bakotic, DPM, DO

While some researchers have suggested that bone tumors affect the feet in a disproportionately small number of cases, one must keep in mind that most major studies on the subject have been assembled at major centers for the treatment of cancer.1,2 Therefore, lesions that have clearly benign clinical or radiologic features are largely omitted. Also be aware that most tumors of the bones of the distal extremities may be readily biopsied or excised, histopathologically evaluated and treated in a community hospital setting. These lesions would similarly never find their way into the files of large cancer centers or consultation services.
In order to identify bone tumors of the feet accurately, one must understand the relative frequency with which various tumors of bone occur in that location. Occasional tumors of bone such as Dupuytren’s (subungual) exostosis occur in the feet in the vast majority of cases. In contrast, osteochondroma, the most common benign bone tumor, is rare in the small bones of the feet.
Though many large bone tumor series have grouped lesions of the hands with those of the feet, even these sites are affected at different rates. In 1997, Ostrowski and Spjut published a series of 240 “lesions” of the bones of the hands and feet.3 They noted a relatively large number of reactive or reparative lesions of bone within their series. They identified conditions such as florid reactive periostitis, bizarre parosteal osteochondromatous proliferation (Nora’s lesion) and giant cell reparative granuloma at a much higher rate than has been described outside of the hands and feet.3

Alternate investigators have recorded similar findings and added Dupuytren’s (subungual) exostosis to their list of reactive lesions.4 A curious finding in the series by Ostrowski and Spjut was the paucity of Dupuytren’s (subungual) exostosis among their reported cases as it only accounted for one of the 240 cases in their series.3 The authors did not elaborate on this finding or why osteochondromas outnumbered Dupuytren’s exostosis six to one among their cases, although these findings seem to contrast sharply with other reports on the subject.1,4-6 It is reasonable to assume that at least some Dupuytren’s exostoses in their series were misdiagnosed as osteochondromas.
In keeping with the high number of reactive or reparative bone lesions that have been reported in the bones of the hands and feet, there is an overwhelming predominance of benign lesions, as compared to malignant lesions, in these locations. The ratio of benign to malignant in various series has ranged from 5:1 to 21:1.3,4 This ratio differed somewhat from the 1.2:1 benign to malignant ratio reported in a series of pedal bone tumors assembled at the Memorial Sloan-Kettering Cancer Center.5
The authors of this latter series attributed the relatively few benign lesions in their study to the fact that their cases were assembled in a center that specializes in the treatment of cancer. This source certainly led to a bias toward malignant tumors by largely eliminated lesions that were radiologically, and/or histopathologically, benign from their series.
For the purpose of discussion, we’ll divide bone lesions of the small bones of the feet into three categories: reactive/reparative lesions, benign neoplasms and malignant neoplasms. The prevailing thinking is that reactive/reparative lesions of bone are non-neoplastic proliferations or hyperplasias that are incited by trauma or stress in most cases. In contrast, neoplasms are autologous new growths that are clonal in nature in that they emanate from a single genetically identical “mother cell.” In most cases, neoplasms do not form in response to trauma or involute upon removal of a stimulus.

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