<p>Sir,</p> <p>With great interest, we read the recent article "Fetus in fetu: A rare case report" by Sharma et al. <sup> <xref ref-type="bibr" rid="ref1">1</xref> </sup>Herein, we would like to add another case of fetus in fetu in abdomen and emphasize the preoperative diagnosis by computed tomography (CT) in such patients.</p> <p>A 17-month-old male child was brought to our department by his parents when they noticed a lump in the lower abdomen for last 3 days. Abdominal ultrasonography (US) revealed a large, hyperechoic, and heterogeneous mass, measuring about 56 mm × 34 mm × 48 mm, in the lower abdomen. Then, CT scan was performed to verify a large, complex, soft-tissue mass with bony elements <xref ref-type="fig" rid="F1">Figure 1</xref>. At laparotomy, a well-encapsulated retroperitoneal mass was found. Then, in toto excision of the mass was performed. On microscopic evaluation, well-developed vertebral and extremity bones plus differentiated connective and fat tissues were revealed. Based on the histopathology, a final diagnosis of fetus in fetu was confirmed. <fig id="F1"> <label>Figure 1</label> <caption> <p>Abdominal CT at different levels (a: Axial; b: Coronal; c: Sagittal) revealed a large, complex, soft-tissue mass with bony elements (white arrow)</p> </caption> <alt-text>Figure 1</alt-text> <graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="JResMedSci_2013_18_10_924_124925_f1.tif" /> </fig></p> <p>The term "fetus in fetu" was first described by Johann Friedrich Meckel in 1800 and defined by Willis in 1953 as a rare condition where a malformed parasitic twin resides in the body of its host. <sup> <xref ref-type="bibr" rid="ref2">2</xref> </sup>However, there is controversy as to whether fetus in fetu is a distinct entity or represents a highly organized teratoma. Spencer <sup> <xref ref-type="bibr" rid="ref3">3</xref> </sup>suggested that a fetus in fetu must have one or more of the following conditions: (1) be enclosed within a distinct sac; (2) be partially or completely covered by normal skin; (3) have grossly recognizable anatomic parts; (4) be attached to the host by only a few relatively large blood vessels; (5) either be located immediately adjacent to one of the sites of attachment of conjoined twins or be associated with the neural tube or the gastrointestinal system. The cardinal differential point of fetus in fetu from mature teratoma is the presence of vertebral column along with the presence of complex and well-differentiated tissues. <sup> <xref ref-type="bibr" rid="ref4">4</xref> </sup>, <sup> <xref ref-type="bibr" rid="ref5">5</xref> </sup></p> <p>We agree with Sharma et al. <sup> <xref ref-type="bibr" rid="ref1">1</xref> </sup>that CT scan is a very useful imaging modality in preoperative diagnosis. Identification of the vertebral column and the long bones of limbs in CT scan is an important indication for the diagnosis of fetus in fetu. <sup> <xref ref-type="bibr" rid="ref6">6</xref> </sup>, <sup> <xref ref-type="bibr" rid="ref7">7</xref> </sup></p> </sec> </body> <back> <ref-list> <ref id="ref1"> <label>1</label> <nlm-citation citation-type="journal"> <person-group person-group-type="author"> <name> <surname>Sharma</surname> <given-names>A</given-names> </name> <name> <surname>Goyal</surname> <given-names>A</given-names> </name> <name> <surname>Sharma</surname> <given-names>S</given-names> </name> </person-group> <article-title>Fetus in fetu: A rare case report</article-title> <source>J Res Med Sci</source> <year>2012</year> <volume>17</volume> <fpage>491</fpage> <lpage>4</lpage> </nlm-citation> </ref> <ref id="ref2"> <label>2</label> <nlm-citation citation-type="journal"> <person-group person-group-type="author"> <name> <surname>Willis</surname> <given-names>RA</given-names> </name> </person-group> <article-title>The borderland of embryology and pathology.Washington, DC: Butterworths; 1962</article-title> <source>p</source> <year></year> <volume></volume> <fpage></fpage> <comment>The borderland of embryology and pathology Washington, DC: Butterworths; 1962 p 442-62</comment> </nlm-citation> </ref> <ref id="ref3"> <label>3</label> <nlm-citation citation-type="journal"> <person-group person-group-type="author"> <name> <surname>Spencer</surname> <given-names>R</given-names> </name> </person-group> <article-title>Parasitic conjoined twins: External, internal (fetuses in fetu and teratomas), and detached (acardiacs)</article-title> <source>Clin Anat</source> <year>2001</year> <volume>14</volume> <fpage>428</fpage> <lpage>44</lpage> </nlm-citation> </ref> <ref id="ref4"> <label>4</label> <nlm-citation citation-type="journal"> <person-group person-group-type="author"> <name> <surname>Federici</surname> <given-names>S</given-names> </name> <name> <surname>Ceccarelli</surname> <given-names>PL</given-names> </name> <name> <surname>Ferrari</surname> <given-names>M</given-names> </name> <name> <surname>Galli</surname> <given-names>G</given-names> </name> <name> <surname>Zanetti</surname> <given-names>G</given-names> </name> <name> <surname>Domini</surname> <given-names>R</given-names> </name> </person-group> <article-title>Fetus in fetu: Report of three cases and review of the literature</article-title> <source>Pediatr Surg Int</source> <year>1991</year> <volume>6</volume> <fpage>60</fpage> <lpage>5</lpage> </nlm-citation> </ref> <ref id="ref5"> <label>5</label> <nlm-citation citation-type="journal"> <person-group person-group-type="author"> <name> <surname>Mohta</surname> <given-names>A</given-names> </name> <name> <surname>Khurana</surname> <given-names>N</given-names> </name> </person-group> <article-title>Fetus-in-fetu or well-differentiated teratoma-a continued controversy</article-title> <source>Indian J Surg</source> <year>2011</year> <volume>73</volume> <fpage>372</fpage> <lpage>4</lpage> </nlm-citation> </ref> <ref id="ref6"> <label>6</label> <nlm-citation citation-type="journal"> <person-group person-group-type="author"> <name> <surname>Luzzatto</surname> <given-names>C</given-names> </name> <name> <surname>Talenti</surname> <given-names>E</given-names> </name> <name> <surname>Tregnaghi</surname> <given-names>A</given-names> </name> <name> <surname>Fabris</surname> <given-names>S</given-names> </name> <name> <surname>Scapinello</surname> <given-names>A</given-names> </name> <name> <surname>Guglielmi</surname> <given-names>M</given-names> </name> </person-group> <article-title>Double fetus in fetu: Diagnostic imaging</article-title> <source>Pediatr Radiol</source> <year>1994</year> <volume>24</volume> <fpage>602</fpage> <lpage>3</lpage> </nlm-citation> </ref> <ref id="ref7"> <label>7</label> <nlm-citation citation-type="journal"> <person-group person-group-type="author"> <name> <surname>Vasani</surname> <given-names>PK</given-names> </name> <name> <surname>Soni</surname> <given-names>HC</given-names> </name> <name> <surname>Murali Krishnan</surname> <given-names>NN</given-names> </name> <name> <surname>Vadodaria</surname> <given-names>H</given-names> </name> <name> <surname>Goswami</surname> <given-names>KG</given-names> </name> </person-group> <article-title>Fetus-infetu--a case report</article-title> <source>Abdom Imaging</source> <year>2010</year> <volume>35</volume> <fpage>504</fpage> <lpage>6</lpage> </nlm-citation> </ref> <ref id="ref8"> <label>8</label> <nlm-citation citation-type="journal"> <person-group person-group-type="author"></person-group> <article-title></article-title> <source></source> <year></year> <volume></volume> <fpage></fpage> </nlm-citation> </ref> </ref-list> </back> </article>

JRMS

J Res Med Sci

Journal of Research in Medical Sciences

1735-1995 1735-7136

Medknow Publications Pvt Ltd

India

JRMS-18-924

24497870

Letter to Editor

Fetus in fetu: A rare presentation

Huang

Ying

Zhang

Qiong

Feng

Ji-Feng

Liu

Jing

Department of Nursing, Zhejiang Cancer Hospital, Hangzhou, China Department of Nursing, Zhejiang Cancer Hospital, Hangzhou, China Department of Oncological Surgery, Zhejiang Cancer Hospital, Hangzhou, China Department of General Surgery, Southeast Hospital, Xiamen University, Zhangzhou, China

Address for correspondence:Ji-Feng Feng, Department of Oncological Surgery, Zhejiang Cancer Hospital, No. 38, Guangji Road, Hangzhou, China fengjif@163.com

October 2013

18 10 924 925

2013

This is an open-access article distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

<p>Sir,</p> <p>With great interest, we read the recent article "Fetus in fetu: A rare case report" by Sharma et al. <sup> <xref ref-type="bibr" rid="ref1">1</xref> </sup>Herein, we would like to add another case of fetus in fetu in abdomen and emphasize the preoperative diagnosis by computed tomography (CT) in such patients.</p> <p>A 17-month-old male child was brought to our department by his parents when they noticed a lump in the lower abdomen for last 3 days. Abdominal ultrasonography (US) revealed a large, hyperechoic, and heterogeneous mass, measuring about 56 mm × 34 mm × 48 mm, in the lower abdomen. Then, CT scan was performed to verify a large, complex, soft-tissue mass with bony elements <xref ref-type="fig" rid="F1">Figure 1</xref>. At laparotomy, a well-encapsulated retroperitoneal mass was found. Then, in toto excision of the mass was performed. On microscopic evaluation, well-developed vertebral and extremity bones plus differentiated connective and fat tissues were revealed. Based on the histopathology, a final diagnosis of fetus in fetu was confirmed. <fig id="F1"> <label>Figure 1</label> <caption> <p>Abdominal CT at different levels (a: Axial; b: Coronal; c: Sagittal) revealed a large, complex, soft-tissue mass with bony elements (white arrow)</p> </caption> <alt-text>Figure 1</alt-text> <graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="JResMedSci_2013_18_10_924_124925_f1.tif" /> </fig></p> <p>The term "fetus in fetu" was first described by Johann Friedrich Meckel in 1800 and defined by Willis in 1953 as a rare condition where a malformed parasitic twin resides in the body of its host. <sup> <xref ref-type="bibr" rid="ref2">2</xref> </sup>However, there is controversy as to whether fetus in fetu is a distinct entity or represents a highly organized teratoma. Spencer <sup> <xref ref-type="bibr" rid="ref3">3</xref> </sup>suggested that a fetus in fetu must have one or more of the following conditions: (1) be enclosed within a distinct sac; (2) be partially or completely covered by normal skin; (3) have grossly recognizable anatomic parts; (4) be attached to the host by only a few relatively large blood vessels; (5) either be located immediately adjacent to one of the sites of attachment of conjoined twins or be associated with the neural tube or the gastrointestinal system. The cardinal differential point of fetus in fetu from mature teratoma is the presence of vertebral column along with the presence of complex and well-differentiated tissues. <sup> <xref ref-type="bibr" rid="ref4">4</xref> </sup>, <sup> <xref ref-type="bibr" rid="ref5">5</xref> </sup></p> <p>We agree with Sharma et al. <sup> <xref ref-type="bibr" rid="ref1">1</xref> </sup>that CT scan is a very useful imaging modality in preoperative diagnosis. Identification of the vertebral column and the long bones of limbs in CT scan is an important indication for the diagnosis of fetus in fetu. <sup> <xref ref-type="bibr" rid="ref6">6</xref> </sup>, <sup> <xref ref-type="bibr" rid="ref7">7</xref> </sup></p> </sec> </body> <back> <ref-list> <ref id="ref1"> <label>1</label> <nlm-citation citation-type="journal"> <person-group person-group-type="author"> <name> <surname>Sharma</surname> <given-names>A</given-names> </name> <name> <surname>Goyal</surname> <given-names>A</given-names> </name> <name> <surname>Sharma</surname> <given-names>S</given-names> </name> </person-group> <article-title>Fetus in fetu: A rare case report</article-title> <source>J Res Med Sci</source> <year>2012</year> <volume>17</volume> <fpage>491</fpage> <lpage>4</lpage> </nlm-citation> </ref> <ref id="ref2"> <label>2</label> <nlm-citation citation-type="journal"> <person-group person-group-type="author"> <name> <surname>Willis</surname> <given-names>RA</given-names> </name> </person-group> <article-title>The borderland of embryology and pathology.Washington, DC: Butterworths; 1962</article-title> <source>p</source> <year></year> <volume></volume> <fpage></fpage> <comment>The borderland of embryology and pathology Washington, DC: Butterworths; 1962 p 442-62</comment> </nlm-citation> </ref> <ref id="ref3"> <label>3</label> <nlm-citation citation-type="journal"> <person-group person-group-type="author"> <name> <surname>Spencer</surname> <given-names>R</given-names> </name> </person-group> <article-title>Parasitic conjoined twins: External, internal (fetuses in fetu and teratomas), and detached (acardiacs)</article-title> <source>Clin Anat</source> <year>2001</year> <volume>14</volume> <fpage>428</fpage> <lpage>44</lpage> </nlm-citation> </ref> <ref id="ref4"> <label>4</label> <nlm-citation citation-type="journal"> <person-group person-group-type="author"> <name> <surname>Federici</surname> <given-names>S</given-names> </name> <name> <surname>Ceccarelli</surname> <given-names>PL</given-names> </name> <name> <surname>Ferrari</surname> <given-names>M</given-names> </name> <name> <surname>Galli</surname> <given-names>G</given-names> </name> <name> <surname>Zanetti</surname> <given-names>G</given-names> </name> <name> <surname>Domini</surname> <given-names>R</given-names> </name> </person-group> <article-title>Fetus in fetu: Report of three cases and review of the literature</article-title> <source>Pediatr Surg Int</source> <year>1991</year> <volume>6</volume> <fpage>60</fpage> <lpage>5</lpage> </nlm-citation> </ref> <ref id="ref5"> <label>5</label> <nlm-citation citation-type="journal"> <person-group person-group-type="author"> <name> <surname>Mohta</surname> <given-names>A</given-names> </name> <name> <surname>Khurana</surname> <given-names>N</given-names> </name> </person-group> <article-title>Fetus-in-fetu or well-differentiated teratoma-a continued controversy</article-title> <source>Indian J Surg</source> <year>2011</year> <volume>73</volume> <fpage>372</fpage> <lpage>4</lpage> </nlm-citation> </ref> <ref id="ref6"> <label>6</label> <nlm-citation citation-type="journal"> <person-group person-group-type="author"> <name> <surname>Luzzatto</surname> <given-names>C</given-names> </name> <name> <surname>Talenti</surname> <given-names>E</given-names> </name> <name> <surname>Tregnaghi</surname> <given-names>A</given-names> </name> <name> <surname>Fabris</surname> <given-names>S</given-names> </name> <name> <surname>Scapinello</surname> <given-names>A</given-names> </name> <name> <surname>Guglielmi</surname> <given-names>M</given-names> </name> </person-group> <article-title>Double fetus in fetu: Diagnostic imaging</article-title> <source>Pediatr Radiol</source> <year>1994</year> <volume>24</volume> <fpage>602</fpage> <lpage>3</lpage> </nlm-citation> </ref> <ref id="ref7"> <label>7</label> <nlm-citation citation-type="journal"> <person-group person-group-type="author"> <name> <surname>Vasani</surname> <given-names>PK</given-names> </name> <name> <surname>Soni</surname> <given-names>HC</given-names> </name> <name> <surname>Murali Krishnan</surname> <given-names>NN</given-names> </name> <name> <surname>Vadodaria</surname> <given-names>H</given-names> </name> <name> <surname>Goswami</surname> <given-names>KG</given-names> </name> </person-group> <article-title>Fetus-infetu--a case report</article-title> <source>Abdom Imaging</source> <year>2010</year> <volume>35</volume> <fpage>504</fpage> <lpage>6</lpage> </nlm-citation> </ref> <ref id="ref8"> <label>8</label> <nlm-citation citation-type="journal"> <person-group person-group-type="author"></person-group> <article-title></article-title> <source></source> <year></year> <volume></volume> <fpage></fpage> </nlm-citation> </ref> </ref-list> </back> </article>