|Year : 2017 | Volume
| Issue : 3 | Page : 193-195
Pulmonary sclerosing pneumocytoma or sclerosing hemangioma mimicking lung cancer
Vandana Gite, Maruti Dhakane
Department of Lab Services, Apollo Hospitals, Bilaspur, Chhattisgarh, India
|Date of Web Publication||27-Oct-2017|
Department of Lab Services, Apollo Hospitals, Bilaspur, Chhattisgarh
Source of Support: None, Conflict of Interest: None
Pulmonary sclerosing pneumocytoma or sclerosing hemangioma is an uncommon benign neoplasm, often asymptomatic, affects middle-aged women and usually found incidentally as solitary pulmonary nodule on radiologic examination. It is thought to be derived from incompletely differentiated respiratory epithelium. Histologically, it is distinctive neoplasm of the lung and shows two epithelial cell types, surface cells, and round cells with four architectural patterns, papillary, sclerotic, solid, and hemorrhagic. Preoperative diagnosis of this tumor is difficult, and it is now generally accepted that surgical excision alone is curative without the need for additional treatment.
Keywords: Benign, pulmonary sclerosing pneumocytoma, round cells, sclerosing hemangioma, surface cells
|How to cite this article:|
Gite V, Dhakane M. Pulmonary sclerosing pneumocytoma or sclerosing hemangioma mimicking lung cancer. Apollo Med 2017;14:193-5
| Introduction|| |
Pulmonary sclerosing pneumocytoma (PSP) or sclerosing hemangioma (SH) is an uncommon benign neoplasm, often asymptomatic, affects middle-aged women and usually found incidentally. It was first described by Liebow and Hubbel. It is misnomer and originated from morphologic similarity to a dermatopathology lesion that was previously called “SH,”, now known as dermatofibroma/fibrous histiocytoma. It is moved from “miscellaneous tumors” to “adenomas” in 2015 World Health Organization (WHO) Classification.
| Case Report|| |
A 52-year-old female presented with chest pain and cough for 1 month. Computed tomography (CT) chest showed medium-sized, well-defined soft tissue nodule measuring 3.3 cm × 3.0 cm in posterior segment of the right upper lobe with linear fibrotic opacity in lateral aspect. Biopsy was carried out and showed benign lung tumor. Surgical excision was done, and right lung upper lobectomy specimen was received for histopathological examination. Gross examination revealed single, well-circumscribed, solid, gray white, nodule measuring 2.5 cm × 2.5 cm [Figure 1]. On microscopic examination, a well-circumscribed benign tumors composed of double cell population consisting of cuboidal surface epithelial cells, resembling type II pneumocytes, and round to polygonal stromal cells are with abundant eosinophilic cytoplasm, indistinct cell borders, oval nuclei, even chromatin, and indistinct nucleoli [Figure 2]a and [Figure 2]b. No areas of necrosis, apparent nuclear atypia, or mitotic activity were seen. Epithelial membrane antigen (EMA), thyroid transcription factor-1 (TTF-1), S-100, vimentin, and MIC2 stains were positive for immunohistochemistry. Mast cells stained with calretinin and CD117. CD68 was positive in histiocytes. Pan-cytokeratin was positive in few cells. CD34, CD45, smooth muscle actin, desmin, BCL-2, and calponin were negative [Figure 3]a-h]. Final diagnosis of PSP or SH was made.
|Figure 1: Gross showing single, well-circumscribed, solid, gray white, nodule measuring 2.5 cm × 2.5 cm|
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|Figure 2: (a and b) A well-circumscribed benign tumor composed of double cell population consisting of are cuboidal surface epithelial cells, resembling type II pneumocytes, and round to polygonal stromal cells are with abundant eosinophilic cytoplasm|
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|Figure 3: (a-h) Epithelial membrane antigen, thyroid transcription factor-1, S-100, vimentin, and MIC2 stains were positive for immunohistochemistry. Mast cells stained with calretinin and CD117. CD68 was positive in histiocytes. Pan-cytokeratin was positive in few cells|
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| Discussion|| |
PSP or SH is a rare benign tumor with low prevalence. It is not a vascular tumor. It is a misnomer and classified as sclerosing pneumocytoma, moved from “miscellaneous tumors” in the 1999 and 2004 WHO Classification to “adenomas” in the 2015 WHO Classification. The tumor is derived from primitive respiratory epithelial cells of pneumocytic origin and shows resemblance to pneumocytes (surface cells) and embryonic respiratory epithelium (round cells). It is more common in Asia, and most patients are women in the fifth decade. It is reported that sclerosing pneumocytoma of the lung was mainly found incidentally, over 70% of the patients were asymptomatic. The most common presenting form is an asymptomatic solitary pulmonary nodule that can grow up to 7 cm in diameter although 73% of lesions are smaller than 3 cm., It may present with nonspecific respiratory symptoms such as cough, hemoptysis, chest pain, and stuffiness.
Radiologically, it presents as solitary, peripheral, well-defined, rounded to oval, homogeneous mass on chest X-ray. CT shows homogeneous, round to oval, dense mass enhances with contrast and may show calcification and/or cystic changes. CT signs included marginal pseudocapsule (50%), overlying vessel (26.3%), air gap (2.6%), and halo sign (17.1%). Sometimes, pleural-based, polypoidal lesions may mimic solitary fibrous tumor. It can be very challenging to diagnose on frozen sections, small biopsies, and cytology where they can easily be mistaken for adenocarcinoma or carcinoid tumors. Grossly, SH found as well as circumscribed, nonencapsulated, easily shelled out, solid, firm nodule. Cut surface is usually tan-yellow to gray, may be mottled or hemorrhagic, and may show cystic areas. Generally, it is <3 cm but may be larger., Histological morphology of this tumor shows four patterns, may show predominantly one or all four including papillary, sclerotic, solid, and hemorrhagic comprising “surface cells” lining papillae and “round cells” within papillary cores and solid sheets. Surface cells are cuboidal, resembling type II pneumocytes and may show foamy cytoplasm, nuclear pseudoinclusions, and multinucleation. Round cells are polygonal with abundant eosinophilic cytoplasm, indistinct cell borders, oval nuclei, even chromatin, and indistinct nucleoli and may show cytoplasmic vacuolization. The stroma may be sclerotic with hemorrhage and chronic inflammation.
Both surface and round cell stains with EMA and TTF-1 in >90% of cases. However, the round cells are generally uniformly negative for pan-cytokeratin and positive for cytokeratin-7 and CAM 5.2 in few cases. Surfactant proteins A and B as well as Clara cell antigen are positive in varying number of surface cells, but they are negative in the round cells. Neuroendocrine cells either as isolated, scattered cells or as a tumorlet within the center of SH may be detected (chromogranin, Leu-7, and synaptophysin positive). The expression of TTF-1 in the absence of surfactant proteins A and B and Clara cell antigens in the round cells of SH suggests that they are derived from primitive respiratory epithelium. The alveolar pneumocytes and neuroendocrine cells may either represent phenotypic differentiation of a primitive respiratory epithelial component or they may correspond to nonneoplastic entrapped or hyperplastic elements. The concomitant positivity of both cell types in SH for TTF-1 and EMA and the negativity of round cells for pan-cytokeratin and neuroendocrine markers provide useful clues not only for histogenesis but also for the diagnosis of this lung neoplasm. P53 mutation was exhibited in primary SH. The mutation rate in polygonal cells was higher than that in surface cuboidal cells.
| Conclusion|| |
PSP or SH is an uncommon benign neoplasm, often asymptomatic, affects middle-aged women and usually found incidentally. Histologically, it is distinctive neoplasm of the lung and shows two epithelial cell types, surface cells, and round cells with four architectural patterns, papillary, sclerotic, solid, and hemorrhagic. Preoperative diagnosis of this tumor is difficult, and it is now generally accepted that surgical excision alone is curative without the need for additional treatment.
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[Figure 1], [Figure 2], [Figure 3]