Anat Cell Biol.  2019 Mar;52(1):93-96. 10.5115/acb.2019.52.1.93.

A large thymic mass with persistent active tissue in an elderly cadaver

• Tripathy P
• Chaudhary
• Gaikwad MR
• Britto NJ

• KMID: 2442337
• DOI: http://doi.org/10.5115/acb.2019.52.1.93

Abstract

Thymus is an encapsulated organ having its bilateral origin from the third pharyngeal pouch. It appears to be a single organ but actually it is bilobed. It attains its maximum development at puberty and then it begins to involute. The parenchyma is replaced by adipocytes and lymphocyte production declines. Here we present a large thymus with a small area of persistent active tissue in it which was obtained during routine undergraduate dissection class. Tissues taken from different quadrants of the large thymic mass were processed, embedded in paraffin and sections were taken for hematoxylin and eosin staining which showed presence of thymic tissue in only one quadrant. Further sections from that quadrant was treated with cytokeratin to confirm its epithelial origin. Therefore knowledge of a large persistent thymus will be helpful to the radiologists and surgeons for making differential diagnosis and in avoiding unnecessary surgical intervention.

Keyword

Thymus; Mediastinal mass; Fatty infiltration; Immunohistochemistry

MeSH Terms

Adipocytes
Adolescent
Aged*
Cadaver*
Diagnosis, Differential
Eosine Yellowish-(YS)
Hematoxylin
Humans
Immunohistochemistry
Keratins
Lymphocytes
Paraffin
Puberty
Surgeons
Thymus Gland
Eosine Yellowish-(YS)
Hematoxylin
Keratins
Paraffin

Figure

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  Fig. 1 (A) Presence of a large thymic mass in the anterior mediastinum lying in front of pericardium and in between right (Rt. L) and left (Lt. L) lung. (B) Right and left lobes of the thymus were separated only in its lower part. (C) Thymus removed along with its blood supply. AAV, arch of azygous vein; ITV, internal thoracic vessel; LBV, left brachiocephalic vein; RBV, right brachiocephalic vein; Th, thymus; H, heart.

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  Fig. 2 (A) The right (Rt.) and left (Lt.) lobes of the large thymic mass were divided into nine quadrants. (B) Hematoxylin and eosin stained section of eighth quadrant of Rt. lobe of thymus showing persistence of thymic tissue (a), blood vessel (b), and fatty infiltration (c). Scale bar=10 µm.

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  Fig. 3 (A–C) Epithelial cells stained intensely with cytokeratin antibody in section obtained from the eighth quadrant of right lobe of thymus suggesting persistence of active tissue in it.

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