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CASE REPORT Table of Contents   
Year : 2008  |  Volume : 51  |  Issue : 2  |  Page : 225-227
An autopsy report of a rare pediatric lung tumor: Pleuropulmonary blastoma


1 Department of Histopathology, Postgraduate Institute of Medical Education and Research, (PGIMER), Chandigarh, India
2 Department of Pediatrics, Postgraduate Institute of Medical Education and Research, (PGIMER), Chandigarh, India

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   Abstract 

An autopsy report of pleuropulmonary blastoma (PPB) is described in a two-and-a-half-year-old male child who died within a few days of starting chemotherapy. Autopsy revealed a large tumor almost occupying the whole of left hemithorax with widespread extension to pleura. The diagnosis was confirmed to be PPB, type III on autopsy.

Keywords: Anaplasia, autopsy, pleuropulmonary blastoma

How to cite this article:
Gupta K, Vankalakunti M, Das A, Marwaha RK. An autopsy report of a rare pediatric lung tumor: Pleuropulmonary blastoma. Indian J Pathol Microbiol 2008;51:225-7

How to cite this URL:
Gupta K, Vankalakunti M, Das A, Marwaha RK. An autopsy report of a rare pediatric lung tumor: Pleuropulmonary blastoma. Indian J Pathol Microbiol [serial online] 2008 [cited 2019 Dec 11];51:225-7. Available from: http://www.ijpmonline.org/text.asp?2008/51/2/225/41663



   Introduction Top


Pleuropulmonary blastoma (PPB) is a unique dysontogenetic neoplasm of childhood that appears as a pulmonary and/or pleural-based mass and is characterized histologically by a primitive, variably mixed blastematous and sarcomatous appearance. [1] These are rare primary malignancies of the lung, accounting for 0.25-0.5% of primary lung tumors. [1]

These consist primarily of immature epithelial and mesenchymal components and histopathologically resemble the epithelial and stromal components of the fetal lung in the pseudoglandular stage of development. Originally called 'pulmonary embryomas' by Barnard, [2] Spencer [3] later designated these tumors as 'pulmonary blastomas', suggesting an origin from the pulmonary blastema or a pluripotential mesenchyme. PPB is a rare and unique early childhood malignancy and most cases of PPB (93%) are diagnosed in children less than 6 years of age.

These have been subclassified into PPB type I, II and III as described by Dehner et al. [4] Type I PPB is exclusively cystic without a grossly detectable solid component, type III PPB is a solid tumor without epithelial-lined cystic spaces and type II PPB exhibits both solid and cystic areas that are identifiable on gross inspection.

Recently, a further distinctive feature of PPB has been found with the observation that 25% of cases occur in a constitutional/familial setting, in which the PPB patients themselves or young family members have other dysplastic or neoplastic conditions. [5] Hence, there is a need for correct diagnosis for effective and timely management of these patients and this also has a bearing on other siblings.

In this brief communication, we describe the autopsy findings in a young male child with PPB who succumbed to his illness within 3 days of initiating chemotherapy.


   Case History Top


A two-and-a-half-year-old male child presented with 4-week history of increasing breathlessness, loss of weight and appetite. On examination, the respiratory rate was 58/min with nasal flare and intercostal retraction. There was no hepatosplenomegaly or peripheral lymphadenopathy. A chest X-ray revealed fluffy opacities in the right lung. The left hemithorax was opaque with aeration in upper part only. Fine needle aspiration cytology and core biopsy revealed a small round cell tumor with morphology consistent with PPB. Combination chemotherapy with vincristine, adriamycin and cyclophosphamide (VAC) was administered. Anuria, metabolic acidosis and bradycardia were documented before he succumbed to his illness.

A complete autopsy was performed after an informed consent. The serous cavities were within normal limits. The lungs together weighed 260 g. The lower lobe of the left lung was densely adherent to the chest wall and diaphragm and was completely replaced by a large necrotic tumor mass measuring 12 ◊ 7.5 ◊ 6 cm [Figure 1A]. It was partly covered by pleura, which was thickened anteriorly. The tumor was displacing the heart to the right. On cut surface, the tumor was largely necrotic with preserved grey white soft areas in the periphery. No gelatinous foci suggestive of cartilaginous differentiation were identified on gross examination. The upper lobe of both left and right lung was subcrepitant. On microscopic examination, the tumor was sharply demarcated from the surrounding lung parenchyma [Figure 1B]. It was composed of sheets of immature primitive tumor cells with moderately pleomorphic round to oval, hyperchromatic nuclei [Figure 1C]. A significant degree of cellular anaplasia in the form of giant, bizarre cells with hyperchromatic nuclei and some with multinucleation were present extensively constituting approximately 80% of the tumor area [Figure 1D]. Occasional areas of cystic degeneration that lacked epithelial lining were noted. However, no well-defined cysts with ciliated epithelium were seen. Many thin-walled capillary channels were present interspersed in between giving a vague nodular appearance. Focal areas revealed cartilaginous differentiation in form of chondroid matrix and few small islands of hyaline cartilage [Figure 1E]. Besides the presence of cartilage seen focally, no areas suggestive of any other mesenchymal differentiation (rhabdomyoblastic or lipomatous) were identified. Many bizarre mitotic figures were noted as well. The neoplastic cells showed cytoplasmic positivity for vimentin. Immunostaining for Mic-2 and for desmin were negative in the tumor cells. Immunostaining for myoglobin and myogenin was not done. The PPB was predominantly solid belonging to type III subcategory.

All the other organs including kidney, heart, GIT, adrenal, liver, spleen and brain were essentially normal on gross and microscopic examination. No tumor metastasis was seen in any of these organs.


   Discussion Top


Dysembryonic or dysontogenetic neoplasms are a unique category of tumors observed exclusively in childhood; examples are Wilms' tumor, neuroblastoma and hepatoblastoma. PPB was described by Manivel et al. [6] as a distinctive intrathoracic/pulmonary neoplasm, where both the blastematous and sarcomatous components coexist as compared to the typical biphasic epithelial-stromal morphology seen in classic adult type pulmonary blastoma. PPB in children differs from its counterpart in adults because of its variable anatomic location, primitive embryonic-like blastema and stroma, absence of a carcinomatous component and potential for sarcomatous differentiation. The designation of PPB is suggested by the authors for these intrathoracic neoplasms of childhood rather than pulmonary blastoma for histogenetic and anatomic reasons. [6]

PPB can be divided into three morphologic types or subtypes based on the cystic, cystic and solid, or solid character of the tumor as determined by the gross and microscopic examination. The exclusively cystic or type I PPB is the least complex and presents at an earlier age than either the type II or type III PPB. [1] The PPB in the present case had predominantly solid blastematous component and belongs to the type III subcategory. Few foci of cartilaginous differentiation were found. No areas suggestive of rhabdomyoblastic or lipomatous differentiation were found. Cellular anaplasia in the form of giant, bizarre-appearing pleomorphic cells has been described to be focally present in cases of type II/III PPB. [1] Anaplastic cells constituting >80% of the blastematous areas were observed in the present case. Autopsy case reports cited in the literature document widespread visceral metastatic deposits to CNS, bone, liver and soft tissues. No visceral metastatic deposits were noted in the present case. The cytoplasmic positivity for vimentin in the blastemal component further confirmed its mesenchymal derivative. The negativity for Mic-2 ruled out a primitive neuroectodermal tumor occurring at this site with which this tumor is often confused.

Literature review cites case reports of presumed PPB occurring in preexisting cystic lung lesions, including congenital adenomatoid malformation (CAM), extralobar sequestration and bronchogenic cysts. [7] It is also hypothesized that PPB may arise in a precursor developmental anomaly similar to the relationship of nephrogenic rests and nephroblastomatosis to Wilms' tumor. The progression of CAM to PPB is yet to be proved and these two entities are said to be curiously associated.

The histogenesis of PPB is still undetermined. Yousem et al. [8] observed simultaneous expression of cytokeratin and vimentin in the blastematous component, which provides some support to the concept that a pluripotential blastema may give rise to the epithelial and mesenchymal elements of PPB. It has also been suggested that PPB originates from residual embryonic tissue in the lung, which through genetic and/or environmental influences generates pluripotential cells with different degrees of differentiation. Since the lung is primarily a foregut derivative, further studies of the antigen profile of the embryonal foregut are needed to better understand the histogenesis of this rare tumor.

Reports have documented that the post-chemotherapy resection specimens showed more maturation of rhabdomyoblasts and more nuclear pleomorphism in all mesenchymal cell lines, compared with biopsies sampled before treatment. [9] The tumor in the present case revealed increased nuclear pleomorphism in the blastemal cells compared to the biopsy sample; however, no increased maturation in the mesenchymal cell line was noted.

There is a dramatic better outcome of type I PPB compared to the other two types; [10] however, the overall prognosis of patients with PPB remains poor. Types II and III PPB are aggressive malignancies with overall survival of 62% at 2 years and 42% at 5 years, even after multimodality therapy. [1]

Recent report of this malignancy occurring in a constitutional/familial setting, with the oncogenetic factors coming into play in 25% of cases, has further substantiated the need for thorough family history and correct morphologic diagnosis for timely intervention. [5]

The rarity of PPB has hindered the understanding of its pathology, clinical manifestations and response to therapy of this tumor. Moreover, the disease can express itself through a spectrum of either precursor or premalignant cystic changes that may be manifested in the youngest affected patient. Review of literature cites only few autopsy reports in PPB. Documentation of such cases will help in providing better insights into the tumor morphology, histogenesis and behavior, which will enable early diagnosis and timely management. Moreover, predominance of anaplastic areas within the tumor can often be misleading and should be kept in mind for a correct interpretation.

 
   References Top

1.Priest JR, McDermott MB, Bhatia S, Watterson J, Manivel JC, Dehner LP. Pleuropulmonary blastoma: A clinicopathologic study of 50 cases. Cancer 1997;80:147-61.  Back to cited text no. 1  [PUBMED]  [FULLTEXT]
2.Barnard WG. Embryoma of the lung. Thorax 1952;7:229-301.  Back to cited text no. 2    
3.Spencer H. Pulmonary blastomas. J Pathol Bacteriol 1961;82:161-5.  Back to cited text no. 3    
4.Dehner LP, Watterson J, Priest J. Pleuropulmonary blastoma: A unique intrathoracic pulmonary neoplasm of childhood. Perspect Pediatr Pathol 1995;18:214-26.  Back to cited text no. 4    
5.Boman F, Hill DA, Williams GM, Chauvenet A, Fournet JC, Soglio DB, et al. Familial association of pleuropulmonary blastoma and cystic nephroma and other renal tumors: A report from international Pleuropulmonary Blastoma Registry. J Pediatr 2006;149:850-4.  Back to cited text no. 5  [PUBMED]  [FULLTEXT]
6.Manivel JC, Priest JR, Watterson J, Steiner M, Woods WG, Wick MR, et al. Pleuropulmonary blastoma: The so-called pulmonary blastoma of childhood. Cancer 1988;62:1516-26.  Back to cited text no. 6  [PUBMED]  
7.Murphy JJ, Blair GK, Fraser GC, Ashmore PG, LeBlanc JG, Sett SS, et al. Rhabdomyosarcoma arising within congenital pulmonary cysts: Report of three cases. J Pediatr Surg 1992;27:1364-7.  Back to cited text no. 7  [PUBMED]  [FULLTEXT]
8.Yousem SA, Wick MR, Randhawa P, Manivel JC. Pulmonary blastoma: An immunohistochemical analysis with comparison with fetal lung in its pseudoglandular stage. Am J Clin Pathol 1990;93:167-75.  Back to cited text no. 8  [PUBMED]  
9.Vargas SO, Nosι V, Fletcher JA, Perez-Atayde AR. Gains of chromosome 8 are confined to mesenchymal components in pleuropulmonary blastoma. Pediatr Dev Pathol 2001;4:434-45.  Back to cited text no. 9    
10.Priest JR, Hill DA, Williams GM, Moertel CL, Messinger Y, Finkelstein MJ, et al. Type I Pleuropulmonary blastoma: A report from International Pleuropulmonary Blastoma Registry. J Clin Oncol 2006;24:4492-8.  Back to cited text no. 10  [PUBMED]  [FULLTEXT]

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Correspondence Address:
Kirti Gupta
Department of Histopathology, PGIMER, Chandigarh - 160 012
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0377-4929.41663

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    Figures

  [Figure 1A], [Figure 1B], [Figure 1C], [Figure 1D], [Figure 1E]

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    Abstract
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