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  Table of Contents    
Year : 2021  |  Volume : 64  |  Issue : 1  |  Page : 155-157
Metastatic low-grade myoepithelial carcinoma of lung managed with low-dose external beam radiotherapy

1 Department of Pathology, RGCIRC, New Delhi, India
2 Department of Medical Oncology, RGCIRC, New Delhi, India
3 Department of Radiation Oncology, RGCIRC, New Delhi, India
4 Department of Radiology, RGCIRC, New Delhi, India
5 Department of Nuclear Medicine, RGCIRC, New Delhi, India

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Date of Submission15-Apr-2020
Date of Decision10-May-2020
Date of Acceptance14-Aug-2020
Date of Web Publication8-Jan-2021


Myoepithelial tumor of lung is a rare tumor; the histopathological findings resemble the myoepithelial tumors of the salivary gland. Distinguishing low-grade nonmetastatic myoepithelial carcinoma from benign myoepithelioma can be challenging both radiologically and histomorphologically. We present a case report of a low-grade myoepithelial carcinoma of lung with contralateral lung metastasis which was treated with low-dose external beam radiotherapy

Keywords: Carcinoma, endobronchial, lung, metastasis, myoepithelial, radiotherapy

How to cite this article:
Pasricha S, Bansal D, Batra U, Durga G, Kamboj M, Gupta G, Sharma A, Pahuja A, Jajodia A, Jain V, Gupta M, B. Koyyala VP, Mehta A. Metastatic low-grade myoepithelial carcinoma of lung managed with low-dose external beam radiotherapy. Indian J Pathol Microbiol 2021;64:155-7

How to cite this URL:
Pasricha S, Bansal D, Batra U, Durga G, Kamboj M, Gupta G, Sharma A, Pahuja A, Jajodia A, Jain V, Gupta M, B. Koyyala VP, Mehta A. Metastatic low-grade myoepithelial carcinoma of lung managed with low-dose external beam radiotherapy. Indian J Pathol Microbiol [serial online] 2021 [cited 2022 Jan 20];64:155-7. Available from: https://www.ijpmonline.org/text.asp?2021/64/1/155/306514

   Introduction Top

Myoepithelial tumors of the lung are a rare class of tumors which include benign myoepithelioma and malignant myoepithelial carcinoma (MC). These tumors share the histology and immunohistochemistry (IHC) findings with the myoepithelial tumors of the salivary gland.[1],[2],[3] The histomorphological criteria to distinguish between myoepithelioma and low-grade MC in lung have not been clearly defined and are also difficult to distinguish on clinicoradiological assessment owing to the circumscribed nature of both lesions.[2],[4],[5],[6],[7] As per the prevailing literature, there has been evidence that lower mitotic counts confer a favorable prognosis in MC, while significant high mitotic count and necrosis are associated with metastasis and predict aggressive behavior.[4]

We present a first case report from India of a low-grade MC of lung with contralateral lung metastasis.

   Case History Top

A 66-year-old male, reformed smoker (quitted 20 years back) presented with hemoptysis since 3 months. Bronchoscopy revealed an endobronchial growth in right upper lobe completely occluding the bronchus [Figure 1]. Positron emission tomography-computed tomography (PET-CT) revealed mildly metabolically active endobronchial lesion, 2.8 × 2.8 cm (SUV max 4.9), encasing and attenuating right upper lobe bronchus with distal collapse. Left lung upper lobe showed mildly metabolically active lesion, 4.9 × 1.9 cm (SUV max 5.3), few metabolically inactive lower lobe parenchymal nodules, and few mildly metabolically active level 7 lymph nodes [Figure 2]. Working clinicoradiological findings were suggestive of stage IV lung carcinoma.
Figure 1: Bronchoscopy revealed an endobronchial growth in right upper lobe completely occluding the bronchus

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Figure 2: Fused FDG PET-CT coronal (image a and c) and axial (image b and d) images. The case was diagnosed with myoepithelial carcinoma in lung lesions in staging PET-CT scan (images a and b). Post radiotherapy to right lung lesion PET-CT scan (images c and d) showed response (white arrows) and persistent left lung lesion (white block arrows)

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Right endobronchial biopsy showed respiratory lining with underlying parenchyma infiltrated by neoplastic epithelioid to oval cells arranged in nests, cords, and lattice like configuration with a plasmacytoid nucleus, mild to moderate atypia, few mitosis (2-3/10 hpf). The background stroma was myxohyaline and no necrosis evident [Figure 3]a and [Figure 3]b. Histomorphological features were suggestive of epithelial malignancy favoring nonsmall cell carcinoma (NSCC). On IHC, the tumor cells were strongly positive for cytokeratin 7 (CK7) [Figure 3]d and p40, while negative for TTF-1 and pointed toward the diagnosis of squamous cell carcinoma. However, the morphological features were discordant and were evocative of a salivary gland origin tumor espoused with the findings of an endobronchial location. On further IHC, the tumor cells were strongly positive for SMA and calponin [Figure 3]c. Hence, a final diagnosis of low-grade myoepithelial carcinoma of right lung was established. Histology of left lung largest lesion biopsy was in resonance with above described features, suggestive of metastatic etiology. As these lesions were not endobronchial based, they were considered to be of metastatic nature. We also analyzed 52 genes including EGFR, ALK, ROS-1, ERB-B2, RET, MET, KRAS on multibiomarker next-generation sequencing (NGS) assay (Oncofocus; 52 genes), but no targetable mutation, translocation, or amplification was identified. No membranous expression (0%) was seen on PD-L1 (SP263; Ventana, Roche) immunostain.
Figure 3: (a) Photomicrograph shows an endobronchial biopsy with a tumor located in subepithelial area (H and E; ×40). (b) Tumor cells were arranged in nests and cords with an eccentric nucleus in myxohyaline stroma. Few mitotic figures were seen (H and E; ×400). (c) Calponin was expressed (cytoplasmic positivity) in tumor cells (DAB; ×200). (d) Cytokeratin 7 was expressed in tumor cells (DAB; ×200)

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In view of low-grade features and hemoptysis being the only symptom, after multidisciplinary tumor board (MTB) meeting, the patient was planned for external beam radiotherapy to right lung upper lobe mass (30 Gy/10 fractions). Follow-up PET-CT after 1 month of completion of radiotherapy showed a persistent slightly decreased lesion in right lung (2.5 × 2.4 cm, SUV max 4.2) [Figure 2]. Left lung lesions and lymph nodes were stable. No new lesion was identified. The patient underwent further 3-monthly PET-CT follow-up and is presently asymptomatic after 15 months with stable disease and ECOG performance status grade 0.

   Discussion Top

MC of lung is an extremely rare tumor, shows exclusively myoepithelial differentiation? bereft of any ductal formation.[1],[4] We came across 15 cases on extensively searching the world literature.[8],[9],[10],[11] Majority are seen in males, smokers with an endobronchial mass; age group ranged from fifth to eighth decade in most cases.[2],[3] The endobronchial tumors present with airway obstruction, cough, or hemoptysis while the patients with peripheral lobe tumors may be asymptomatic.[1]

The criteria to differentiate between MC and myoepithelioma are not well described and the diagnosis can be challenging in small endobronchial biopsy in the absence of metastasis. Features favoring malignancy include significant cytological atypia, frequent mitosis, necrosis, infiltrative growth, and metastasis.[2],[3],[5] Other differential diagnosis of MC includes epithelial myoepithelial carcinoma, leiomyoma, and clear cell tumor of lung. The diagnosis of MC requires coexpression of cytokeratin with one myoepithelial marker calponin, S100, CD10, smooth muscle actin (SMA), smooth muscle myosin heavy chain (SMMH), glial fibrillary acidic protein (GFAP), and p63. However, these IHC markers are inconsistently expressed in tumors with myoepithelial differentiation.[2],[3],[8],[10] The presented case expressed p40, SMA, and calponin diffusely and strongly besides histopathological features, hence provided a tangible evidence for myoepithelial differentiation. This case had none of the high-grade features; hence, it was labelled as low-grade MC.

In view of the paucity of cases in literature, there are no standard guidelines for management. Patients with nonmetastatic disease are the candidates for surgery; however, they can show synchronous or? metachronous metastases. The sites for metastases include contralateral lung, liver, brain, and lymph nodes.[2],[3],[5],[10] Almost all the reported cases of MC in the literature underwent surgery.? Miura et al.[5] reported a case in which patient underwent chemotherapy besides surgery without any effective response and patient developed contralateral lung metastasis after 7 months. The presented case had low-grade features and radiotherapy to the right lung endobronchial mass was planned. After 15 months of follow-up, the patient is asymptomatic and recent PET-CT revealed a stable disease in bilateral lungs; hence, the decision for assigning a low grade was? vindicated and obviated the need of toxic chemotherapy.

To conclude, MC of lung, though a rare tumor, should be considered in the differentials of a lung tumor. Diligent evaluation of histopathological features along with clinical and radiological correlation is prudent for accurate diagnosis and assigning the grade, which has distinct therapeutic and prognostic implications, as standard recommendations for therapeutic strategy are difficult to formulate in view of the rarity of these tumors.

Informed Consent

Informed consent was obtained from the participant included in the study.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Travis WD, Fletcher CDM. Myoepithelial tumors/myoepithelial carcinoma. In: Travis WD, Brambilla E, Burke AP, editors. WHO Classification of Tumors of Lung, Pleura, Thymus and Heart. 4th ed. Lyon (France): International Agency for Research on Cancer (IARC) Press; 2015. p. 131.  Back to cited text no. 1
Rosen LE, Singh RI, Vercillo M, Gattuso P. Myoepithelial carcinoma of the lung: A review. Appl Immunohistochem Mol Morphol 2015;23:397-401.  Back to cited text no. 2
Wei J, Yuan X, Yao Y, Sun L, Yao X, Sun A. Primary myoepithelial carcinoma of the lung: A case report and review of literature. Int J Clin Exp Pathol 2015;8:2111-6.  Back to cited text no. 3
Hysi I, Wattez H, Benhamed L, Porte H. Primary pulmonary myoepithelial carcinoma. Interact Cardiovasc Thorac Surg 2011;13:226-8.  Back to cited text no. 4
Miura K, Harada H, Aiba S, Tsutsui Y. Myoepithelial carcinoma of the lung arising from bronchial submucosa. Am J Surg Pathol 2000;24:1300-4.  Back to cited text no. 5
Higashiyama M, Kodama K, Yokouchi H, Takami K, Kabuto T, Tsuji N, et al. Myoepithelioma of the lung: Report of two cases and review of the literature. Lung Cancer 1998;20:47-56.  Back to cited text no. 6
Sarkaria IS, DeLair D, Travis WD, Flores RM. Primary myoepithelial carcinoma of the lung: A rare entity treated with parenchymal sparing resection. J Cardiovasc Surg 2011;6:27.  Back to cited text no. 7
Kridis WB, Toumi N, Khanfir A, Hachicha M, Boudawara T, Frikha M. Primary pulmonary myoepithelial carcinoma in a child: An ambiguous entity. Lung India 2015;32:497-9.  Back to cited text no. 8
[PUBMED]  [Full text]  
Zhou X, Yu M, Zhuo H, Zhang S. Primary pulmonary myoepithelial carcinoma in a young woman: A case report and review of literature. Medicine (Baltimore) 2018;97:e0049.  Back to cited text no. 9
Tanahashi J, Kashima K, Daa T, Yada N, Tanaka K, Kawano Y, et al. Pulmonary myoepithelial carcinoma resembling matrix-producing carcinoma of the breast: Case report and review of the literature. APMIS 2010;118:401-6.  Back to cited text no. 10
Zhang Y, Li B, Hou J, Shi H. Primary myoepithelial carcinoma of the lung and (18)F-FDG PET/CT. Rev Esp Med Nucl Imagen Mol 2018;37:175-7.  Back to cited text no. 11

Correspondence Address:
Divya Bansal
Attending Consultant, Department of Pathology, Rajiv Gandhi Cancer Institute and Research Center (RGCIRC), New Delhi
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/IJPM.IJPM_385_20

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