Pleomorphic rhabdomyosarcoma of the tongue in adult mimicking oral squamous cell carcinoma

Rahmi Amtha¹, Firstine Kelsi Hartanto¹, Walta Gautama², Haizal Mohd Hussaini^3
1 Department of Oral Medicine, Trisakti University, Jakarta, Indonesia
² Department of Oncology, Dharmais National Cancer Hospital, Jakarta Barat, Indonesia
³ Department of Oral Diagnostic and Surgical Sciences, Faculty of Dentistry, University of Otago, Dunedin, New Zealand

Date of Web Publication

18-Jun-2019

Correspondence Address:
Prof Rahmi Amtha
Department of Oral Medicine, Trisakti University, Kyai Tapa Grogol 260, Jakarta 11440
Indonesia

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/SDJ.SDJ_10_19

Abstract

Background: Oral cancer is one of the sixth most common cancers in human, and oral squamous cell carcinoma (OSCC) is the most common type of oral cancer. The clinical appearance of OSCC may resemble other types of oral cancer such as rhabdomyosarcoma (RMS). The definitive diagnosis is crucial as the management and prognosis of both lesions are quite different. Case Report: A 42-year-old male presented with a unhealed painful ulcer of the posterior right lateral border of the tongue for about 4 months. Restricted mobility of the tongue and positive submandibular lymph nodes were detected. Wide excision with regional neck dissection was performed. Discussion:Pleomorphic RMS (PRMS) was identifed by immunohistochemistry of positive desmin and smooth muscle actin. The clinical presentation of the lesion is exactly similar to OSCC. PRMS is a rare type of high-grade sarcoma of the oral cavity. It usually occurs in the deep of lower extremities of adult on the six decade. Conclusion: Although the management of OSCC and RMS is almost alike, the ability of metastasis is salient compared to OSCC. Therefore, the definitive diagnosis should be careful due to its characteristic.

Keywords: Mimicking, oral squamous cell carcinoma, rhabdomyosarcoma

How to cite this article: Amtha R, Hartanto FK, Gautama W, Hussaini HM. Pleomorphic rhabdomyosarcoma of the tongue in adult mimicking oral squamous cell carcinoma. Sci Dent J 2019;3:70-4

How to cite this URL: Amtha R, Hartanto FK, Gautama W, Hussaini HM. Pleomorphic rhabdomyosarcoma of the tongue in adult mimicking oral squamous cell carcinoma. Sci Dent J [serial online] 2019 [cited 2019 Jun 19];3:70-4. Available from: http://www.scidentj.com/text.asp?2019/3/2/70/260557

Background

Oral squamous cell carcinoma (OSCC) is the most common malignancy of the oral cavity. Several risk factors for OSCC have been identified which include tobacco, alcohol, and betel quid chewing. The clinical features of OSCC are commonly presented as ulcerated/papillary/growth-like lesions affecting any part of oral cavity. Once the clinical staging and definitive diagnosis of OSCC via histopathology is established, the clinical management can be done accordingly. On the contrary, soft tissue sarcomas, although rare, can affect approximately 1% of all head-and-neck malignancies.^[1] Rhabdomyosarcoma (RMS) is a malignant soft tissue tumor composed of neoplastic mesenchymal cells, with varying degrees of striated muscle cell differentiation. RMS is more common in young children aged less than 10 years; however, it is less common in adults.^[2] Pleomorphic RMS (PRMS), a subtype of RMS, has a higher prevalence in adults. A clinicopathologic study of 38 cases showed that PRMS is an aggressive form of sarcoma, arising predominantly in the extremities of adult males with a mean age of 49 years and poor survival rate (72% less than 2-year survival rate).^[3] The tumor has a rapid growth rate and typically occurs in the deep soft tissue of the lower extremities. PRMS is remarkably rare to occur in the oral cavity, and currently, there is only one author that reported adult spindle cell-type RMS affecting the floor of the mouth.^[4] Another study reported RMS of the oral cavity that affected buccal mucosa with poor outcome.^[5] Currently, there is no report of PRMS occurring in the tongue or other area of the masticatory appendages.

Histologically, PRMS characteristics are composed of undifferentiated round-to-spindle cells with an admixture of polygonal cells with densely eosinophilic cytoplasm in spindle, tadpole, and racquet-like contours.^[3],[6] These histological features are remarkably different than OSCC, which featured variable degree of keratinization, pleomorphism, and mitotic activity of squamous epithelium with varying degree of differentiation: well, moderate, and poorly differentiated.^[7] Both PRMS and OSCC may have similar clinical presentation, which can be misleading without histopathological investigation. Here, we report a case of a 42-year-old male with PMRS involving tongue with clinical features such as SCC.

Case Report

A 42-year-old male patient presented with a complaint of 4-month duration of a nonhealing ulcer on the right posterior of the tongue with a history of trauma during mastication. Intraoral examination revealed a single ulcerated proliferative lesion, measuring 25 mm × 3 mm with a history of trauma from radix 47. Intraorally, the ulcer is covered with yellowish fibrin with erythematous rolled margin, tender in palpation, and caused pain during conversation and mastication [Figure 1]. Surrounding mucosa, saliva flow appears normal and the oral hygiene was moderate. Extraorally, the right lymph node was palpable. The patient appears cachexia with weight loss of >10 kg in 4 months due to eating difficulties. The working diagnosis was OSCC as the features closely resemble a malignant ulcer [Figure 2].

Figure 1: Yellowish fibrin ulcer with rolled margin of the tongue (diagnosed as PRMS, mimicking an OSCC) Click here to view

Figure 2: The patient with oral squamous cell carcinoma of the tongue Click here to view

The investigative workout (blood test and heart, thorax, and abdominal radiology) showed no occult primary or metastasis elsewhere. Referral to an oncologist was done and operation was planned. Frozen section histopathology was performed during the operation which included a regional neck node dissection. Wide excision of the tongue was done with clear margin as reported by the frozen section examination.

The histology showed malignant tumor located in the connective tissue [Figure 3] composed of round-to-spindle cells admixture with polygonal cells against hyalinized background. The prominent spindle cells showed prominent nuclei and scanty cytoplasm [Figure 4]. “Tadpole” cell was seen [Figure 5]. Immunohistochemistry investigation showed that these tumor cells were strongly positive with smooth muscle actin [Figure 6] and AE1/AE3 [Figure 7] and occasional positivity with desmin [Figure 8] and S-100 [Figure 9]. Ki-67 demonstrated 80% index proliferation [Figure 10]. Myogenin was negative [Figure 11]. Definitive diagnosis of PRMS was established based on immunohistochemistry of desmin and smooth muscle actin positive. Therefore, the patient was planned to undergo chemotherapy and radiotherapy after the operation. Cyclophosphamide and doxorubicin chemotherapy was given for 6 times and radiotherapy 50 Gy for 10 times. The patient has also been referred for a regular speech therapy session. Currently, the patient show good recovery progress with no new tumor detected on 6-month postsurgery [Figure 12]. The patient has agreed to sign informed consent documents before the biopsy was conducted which allowed their cases to be published.

Figure 3: Malignant tumor in the connective tissue (H and E, ×4) Click here to view

Figure 4: Round-to-spindle cells admixture with polygonal cells with prominent nuclei and eosinophilic cytoplasm. (H and E, ×40) Click here to view

Figure 5: “Tadpole” cell was seen  Click here to view

Figure 6: Smooth muscle actin positive (×20) Click here to view

Figure 7: AE1/AE3 positive (×20) Click here to view

Figure 8: Occasional positivity of Desmin (×10) Click here to view

Figure 9: S-100 occasionally positive (×20) Click here to view

Figure 10: Ki-67 demonstrated 80% index proliferation (×20) Click here to view

Figure 11: Myogenin was negative (×20) Click here to view

Figure 12: Six- month postoperation and chemotherapy Click here to view

Discussion

RMS, which was first described by Webner in 1854, is a malignant soft tissue tumor of skeletal muscle origin.^[8] RMS commonly affected areas are the extremities, genitourinary tract, retroperitonium, and head-and-neck region. In the head-and-neck region, RMS usually occurs at the orbit and the oral cavity areas, such as maxillary or mandibular alveolar ridge,^[9],[10] palate,^[11] buccal mucosa,^[5] and tongue. The first publication of RMS in the oral cavity was also reported in 1854,^[12] which was a tongue lesion that has occurred in children. Site predilection in the oral cavity varies among published reports; some reported that the palate, the tongue,^[13] and the orbit, respectively, are the most commonly affected sites in the head-and-neck region. Nasopharynx, middle ear, and soft tissue of the neck are as the second most common site.^[12] RMS frequently affects the children, adolescents, and young adults. In contrast, this case affected posterior tongue of an adult in the fourth decade. RMS in adults is correlated with a poor outcome, and the median survival year is under 2 years.^[2] It differs with OSCC that has 5-year survival rate of more than 50% which improved further with early detection.

Thirty percent of all head-and-neck RMS may arise from intraoral and pharyngeal muscle structures. The tumor tends to extend and invade the muscle from which it arises and presents as a well-demarcated nodule or polypoid lesion with a soft or gummy consistency. Initial symptoms may be uncertain and may mimic other sarcomas such as RMS, alveolar soft-part sarcoma, fibrosarcoma, leiomyosarcoma, and Kaposi sarcoma.^[14] However, their clinical presentation may resemble that of OSCC, one of the most common oral malignancies such as in our case. RMS may present with a smooth or lobulated surface and becomes fixed to surrounding tissues at an early stage.^[14] Clinically, OSCC will present as ulceration due to the damage of the epithelium of oral mucosa and infiltration to submucosal muscle bundle. In our case, the clinical presentation was yellowish-based ulcer with rolled margin, indurated, less painful, with proximity to undetected obvious etiology, which is similar with features of OSCC. Therefore, RMS is hardly the first assumed diagnosis at primary clinical examination. Due to similarity of the clinical presentation to OSCC and the rarity of RMS, clinical misdiagnose may result in mismanagement of the patient and sometime wrong treatment plan. The clinical resemblance of OSCC and RMS highlights the importance of histopathological examination. Both RMS and OSCC have different interpretation in TNM staging, for example, T1 in RMS and OSCC is defined differently. The correct histological diagnosis will also determine the management and prognosis of this malignancy.

There are predominantly three types of RMSs; (1) embryonal variant: approximately 49% of all RMS and affects children aged younger than 10 years. Adolescents and young adults can also be affected and rarely affect those older than 40 years. (2) Alveolar variant: 30% of all RMS and mostly affect patients between 10 and 25 years. Predilection of its variant is deep soft tissues of the extremities. (3) Pleomorphic variant: a rare variant that affect typically in adults older than 40 years. This type of tumor commonly develops in the deep soft tissues of the extremities.^[15] Furlong et al. in 2001 reported that in 38 cases of PRMS in adult, only one affecting the oral cavity.

For the definitive histological interpretation of PRMS, giant cell or multinucleated myoblasts, strap or tadpole cells, and pleomorphic individual tumor cells with or without cross-striations with congested eosinophilic cytoplasm, are some of the common required features. However, in most circumstances, RMS tends to display a wide features of histological presentation with poor differentiation, often making diagnosis and interpretation difficult.^[16]

Majority of oral RMSs are of embryonal type, composed by small, round-to-oval tumor cells with finely granular eosinophilic cytoplasm. Besides, the well differentiation shows elongated, strap-shaped or tadpole-shaped rhabdomyoblasts. Giant cells with enlarged or multiple nuclei can also be found. Mitotic figures are often seen and may be abnormal. The stroma of tumor is minimal and consists of moderately loose to dense fibrous tissue. A pool differentiated shows ovoid mesenchymal cells and myxoid zones of the stroma.^[12] Alveolar RMS is typically consisted of small round densely packed cells, organized around spaces resembling pulmonary alveoli. A solid variant form of alveolar RMS consists of small round densely packed cells without the characteristic alveolar spaces. PRMS is rarely diagnosed and is characterized by pattern less of large amount of anaplastic cells, round cells, and spindle cell.^[14]

Head-and-neck PRMS in adults is a rare malignancy with a poor prognosis compared with other soft tissue sarcomas and OSCC.^[17],[18]Thorough histological interpretation is mandatory to distinguish both lesions from other aggressive lesion affecting tongue.

Conclusion

In this case, histopathological and immunohistochemical examination is mandatory because of clinically resembling OSCC lesions. The marked pleomorphic nuclei and immunohistochemical results (desmin and smooth muscle actin positive) were critical for differentiating PRMS from others. The management needs multidisciplinary case approach in collaboration with colleagues.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understand that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 

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Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12]