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CASE REPORT Table of Contents   
Year : 2009  |  Volume : 52  |  Issue : 2  |  Page : 240-241
Placental site nodule: A tumor-like trophoblastic lesion


Department of Pathology, Christian Medical College and Hospital, Ludhiana, India

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   Abstract 

Placental site nodule is an uncommon, benign, generally asymptomatic lesion of trophoblastic origin, which may often be detected several months to years after the pregnancy from which it resulted. This entity may have bizarre histologic findings and should be distinguished from other aggressive lesions like placental site trophoblastic tumor, epithelioid trophoblastic tumor and squamous cell carcinoma.

Keywords: Gestational trophoblastic diseases, trophoblast, intermediate trophoblast

How to cite this article:
Jacob S, Mohapatra D. Placental site nodule: A tumor-like trophoblastic lesion. Indian J Pathol Microbiol 2009;52:240-1

How to cite this URL:
Jacob S, Mohapatra D. Placental site nodule: A tumor-like trophoblastic lesion. Indian J Pathol Microbiol [serial online] 2009 [cited 2014 Dec 23];52:240-1. Available from: http://www.ijpmonline.org/text.asp?2009/52/2/240/48931



   Introduction Top


Placental site nodule (PSN) is a rare, benign lesion which represents remnants of intermediate trophoblast from a previous gestation that has failed to completely involute [1],[2] Although PSN occurs in the reproductive age group, a temporal association with recent pregnancy is usually lacking and often the time interval between pregnancy and diagnosis of PSN can be several years. These lesions are discovered as incidental findings in curettage or hysterectomy specimens performed for evaluation of irregular uterine bleeding, abnormal cervical smears, post coital bleeding etc. [1],[3],[4] Infertility is a rare mode of presentation in PSN. PSN needs to be differentiated from aggressive lesions of intermediate trophoblast like placental site trophoblastic tumor and epithelioid trophoblastic tumor and from nontrophoblastic diseases like squamous cell carcinoma. [1],[3]


   Case Report Top


A 32 year old female presented with complaints of secondary infertility. She had a full term normal vaginal delivery three years ago. Her menstrual history was unremarkable. There was no history of abortions or irregular bleeding per vaginum since then. General physical examination and routine gynecologic check up were normal. Serum prolactin and progesterone levels were within normal limits. A premenstrual endometrial biopsy was done in order to rule out anovulatory cycles or any other pathology.

Histopathological findings

Adequate endometrial tissue was received. Microscopic examination revealed multiple variable sized, well circumscribed round to ovoid paucicellular eosinophilic nodules of tissue haphazardly distributed amidst fragments of endometrium [Figure 1]. The nodules showed extensive hyalinization, within which were seen cells with indistinct outlines placed in small groups, singly or in cords [Figure 2a]. Some of the cells were small with scant amount of clear cytoplasm and uniform nuclei, while others were larger with pleomorphic, hyperchromatic bizarre nuclei and abundant eosinophilic cytoplasm [Figure 2b]; few multinucleated forms were also present. No mitotic figures were noted. Occasional cells revealed the presence of rounded eosinophilic hyaline bodies in the cytoplasm [[Figure 2] inset]. Periodic acid Schiff (PAS) staining exhibited abundant cytoplasmic glycogen within the small cells. The endometrial glands showed proliferation of the lining epithelium; occasional glands revealed subnuclear vacuoles. No decidua or chorionic villi were present.


   Discussion Top


Gestational trophoblastic disease constitutes a diverse group of lesions, which also includes neoplastic and non-neoplastic proliferations of trophoblast unaccompanied by chorionic villi. [5] A spectrum of lesions derived from the intermediate trophoblast have been described, viz placental site nodule or plaque, exaggerated placental site reaction, placental site trophoblastic tumor and epithelioid trophoblastic tumor. [3],[5] Placental site nodule (PSN) represents remnants of placental site tissue that has failed to involute and may remain in the uterus for several years after the pregnancy from which it resulted. The interval from the most recent known pregnancy till the time of detection ranges widely from one month to 8 years with an average of 3 years. [1] The mean age at diagnosis is in the early thirties with the age range as broad as 20 to 49 years. [2],[3] The clinical indications for surgical evaluation included metro-menorrhagia, hypermenorrhoea, dysmenorrhoea, recurrent abortions, post-coital bleeding, abnormal cervical smear, infertility etc. [1],[3]

Although the overwhelming majority involve the endometrium, PSN can occasionally be seen in the cervix and rarely in the  Fallopian tube More Details and ovary. [3],[6],[7],[8],[9] PSN is generally of microscopic size but when evident grossly, it appears as yellowish or tan surface nodules in the endometrium. The size of the lesion varies from 1mm to 14mm with average of 2.1mm. [3],[4] Microscopically, PSN is characterized by single or multiple, small round or ovoid, well defined extensively hyalinized eosinophilic nodules composed of cords, clusters and single cells of intermediate trophoblast. The cells are small with glycogen rich clear cytoplasm or large with abundant eosinophilic to amphophilic cytoplasm. Nuclear hyperchromatism, multinucleation and degenerative atypia are common, but mitotic figures are rarely seen. [1],[3] Small, round eosinophilic cytoplasmic inclusions and Mallory's hyaline have been described within the trophoblastic cells. [1],[10] PSN is a benign lesion with no evidence of recurrence requiring no specific treatment or follow up. [1],[3]

The differential diagnosis of PSN includes other lesions of intermediate trophoblast like placental site trophoblastic tumor, epithelioid trophoblastic tumor and exaggerated placental site reaction. The small size, presence of well defined, poorly cellular hyaline nodules with paucity of mitotic figures and lack of association with current or recent pregnancy differentiate PSN from these trophoblastic lesions. PSNs are positive for placental alkaline phosphatase and negative/focally positive for Mel-CAM and hpL in contrast to placental site trophoblastic tumors. [4],[5] Exaggerated placental site reaction is distinguished by an admixture of intermediate trophoblast and syncytiotrophoblastic cells laid out in cords and nests and by the absence of hyaline nodules. Placental site trophoblastic tumour differs from PSN by features of trophoblastic infiltration of muscle fibers and vasculotropism. [11] Nontrophoblastic lesions that may be confused with PSN include squamous cell carcinoma. Larger size, greater cytological atypia with mitosis and presence of keratinized cells are pointers towards squamous carcinoma. Additionally, immunoreactivity for inhibin alpha and cytokeratin 18 and a low Ki-67 labeling index favor PSN. [4] PSN has also often been misinterpreted as hyalinized decidua. Decidual cells have more distinct cell membranes, basophilic cytoplasm and pale, uniform nuclei in contrast to the amphophilic or deeply eosinophilic cytoplasm and hyperchromatic, often pleomorphic nuclei of PSN. Intermediate trophoblastic cells are positive for both cytokeratin and hpL, while decidual cells are negative. [1]

To conclude, PSN may have bizarre histologic features necessitating differentiation from aggressive lesions of intermediate trophoblast and from squamous carcinoma. The lack of association with recent pregnancy compounds the problem. Herein lies the importance of this, infrequently encountered, less known benign trophoblastic lesion.

 
   References Top

1.Young RH, Kurman RJ, Scully RE. Placental site nodules and plaques: A clinicopathologic analysis of 20 cases. Am J Surg Pathol 1990;4:1001-9.  Back to cited text no. 1    
2.Huettner PC, Gersell DJ. Placental site nodule: A clinicopathologic study of 38 cases. Int J Gynecol Pathol 1994;13:191-8.  Back to cited text no. 2  [PUBMED]  
3.Shih IM, Seidman JD, Kurman RJ. Placental site nodule and characterization of distinctive types of intermediate trophoblast. Hum Pathol 1999;30:687-94.  Back to cited text no. 3  [PUBMED]  
4.Shih IM, Kurman RJ. The pathology of intermediate trophoblastic tumors and tumor-like lesions. Int J Gynecol Pathol 2001;20:31-47.  Back to cited text no. 4  [PUBMED]  
5.Kurman RJ. The morphology, biology and pathology of intermediate trophoblast: A look back to the present. Hum Pathol 1991;22:847-55.  Back to cited text no. 5  [PUBMED]  
6.Van Dorpe J, Moerman P. Placental site nodule of the uterine cervix. Histopathology 1996;29:379-82.  Back to cited text no. 6  [PUBMED]  
7.Nayer R, Snell J, Silverberg S, Wong LC. Placental site nodule occurring in a fallopian tube. Hum Pathol 1996;27:1243-5.  Back to cited text no. 7    
8.Campello TR, Fittipaldi H, O'Valle F, Carvia RE, Noglaes FF. Extrauterine (tubal) placental site nodule. Histopathology 1998;32:562-5.  Back to cited text no. 8    
9.Al-Hussaini M, Lioe TF, Mc Cluggage WG. Placental site nodule of the ovary. Histopathology 2002;41:471-2.  Back to cited text no. 9    
10.Tsang WY, Chum NP, Tang SK, Tse CC, Chan JK. Mallory's bodies in placental site nodule. Arch Pathol Lab Med 1993;17:547-50.  Back to cited text no. 10    
11.Lage JM. Gestational trophoblastic diseases. In: Robboy SJ, Anderson MC, Russell P, editors. Pathology of the female reproductive tract. 1 st ed. London: Churchill Livingstone Company; 2002. p. 69-70.  Back to cited text no. 11    

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Correspondence Address:
Sunitha Jacob
Department of Pathology, Christian Medical College and Hospital, Ludhiana
India
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DOI: 10.4103/0377-4929.48931

PMID: 19332926

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    Figures

  [Figure 1], [Figure 2a], [Figure 2b], [Figure 2]

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