Abstract

Extracardiac adult rhabdomyoma is a rare benign tumor, which mainly occurs in the head and neck region and originates from striated muscle tissue. We report a 64-year-old male with simultaneous diagnosis of three adult rhabdomyomas including the soft palate and performed a review the literature on multifocal adult rhabdomyoma (mARM). Including the present case, 27 mARM with a range of 2–7 lesions per patient were collected. Mean age at diagnosis was 65 years with a male (23) to female (4) ratio of 5.75:1. Common localizations were parapharyngeal space (35%), larynx (14%), submandibular (13%), paratracheal region (14%), tongue (10%), floor of mouth (9%), neck (3%) and soft palate (2%). In accordance to this review, this the first case of mARM with involvement of the soft palate.

INTRODUCTION

Rhabdomyomas (RM) are amongst the rarest benign tumors in humans. They originate from striated muscles and are classified in cardiac (CR) and extracardiac rhabdomyomas (ER). The cardiac type is commonly associated with genetic abnormalities and appears almost solely in the hearts of infants. In dependence of the skeletal muscle differentiation, ER can be subdivided into a rare fetal (FRM), a more common adult form (ARM)—with preferred occurrence in the head and neck area—and a genital form (GRM) which appears in the vulva and vagina of women. About 3/4 of ER are located in the head and neck area awhile just 14% are found in the genital region [1]. A multifocal adult rhabdomyoma (mARM) is even a more rare tumor. We hereby report the first case of mARM involving the soft palate.

CASE REPORT

A 65-year-old male was referred to our department with a constant urge to clear the throat for a time span of 12 months. In addition, the patient stated his progressing inability to swallow food. Due to these symptoms, a resection of the thyroid gland had been carried out earlier showing struma colloides nodosae as well as bilateral parathyroidal adult rhabdomyomae. Even so, there was no relief in symptoms. At outpatient presentation at his dentist, a slight swelling of the soft palate was felt and the patient was referred for further therapy. Endoscopic examination as well as magnetic resonance imaging (MRI; Fig. 1) unveiled a tumor on the right side of the soft palate with a size of 5 × 5 cm2 and distinct demarcation to the surrounding tissue. Subsequently, the lesion was completely excised (Fig. 2) and histopathological analysis was conducted that showed a circumscribed but not encapsulated mesenchymal tumor with polygonal cell formation. The cells presented a granular cross-striated eosinophilic cytoplasm, large round vesicular nuclei and so called spiderweb cells (Fig. 3). Immunohistochemically, the cytoplasm of the cells was 100% positive for antibodies to desmin and S100 (Fig. 4). Additional immunohistochemical markers showed slight nuclear positivity for myogenin and nuclear negativity for AE1/3, CD68 as well as melan A. The histological examination confirmed ARM without signs of malignancy. At a total follow-up of 3 years, including MRI scan, no signs of recurrence were detected.

MRI scans of ARM involving the soft palate.
Figure 1:

MRI scans of ARM involving the soft palate.

ARM of soft palate after excision.
Figure 2:

ARM of soft palate after excision.

Hematoxylin-eosin (H&E) staining: polygonal cell formation with granular cross-striated eosinophil cytoplasm and large round vesicular nulei are seen.
Figure 3:

Hematoxylin-eosin (H&E) staining: polygonal cell formation with granular cross-striated eosinophil cytoplasm and large round vesicular nulei are seen.

Immunohistological staining of EARM with desmin antibodies. Cytoplasma with positive antibodies for desmin is seen.
Figure 4:

Immunohistological staining of EARM with desmin antibodies. Cytoplasma with positive antibodies for desmin is seen.

DISCUSSION AND REVIEW OF LITERATURE

RM have been first described by Weber [2]. The rare benign tumor originates of striated muscle cells with varying degrees of differentiation and maturity. It can be divided into cardiac and ER. They are the most common primary cardiac tumor in infancy and a rarity in adulthood. Cardiac rhabdomyoma (CR) are more common then extracardiac ones (ER) and are associated with tuberous sclerosis in ~50–80% of cases. CR cause diffuse deformation of the heart muscle; they are seen as hamartoma and regress in ~50% spontaneously.

ER can be classified in fetal rhabdomyoma (FRM), adult rhabdomyoma (ARM) and genital rhabdomyoma (GRM). ARM are more common in male than in female (ratio 4:1) and usually found in the head and neck region (~90%) but they can be found in extremities as well. The mean age at the time of diagnosis is 50 years. Typically, ARM are solitary tumors which can occur multinodular in the same anatomic region [3, 4]. The first clinical signs of ARM are globus sensation, hoarseness, soft painless slow growing mass, dysphagia or other symptoms related to the location of the tumor in the aerodigestive tract. In CT scans, EARM can be misinterpreted as malignant tumors because of their indistinct borders blending into adjacent isodense muscles while presenting itself as slightly hyperdense homogenous lesions. In T1- and T2-weighted MRI, the tumors are isointense or slightly hyperintense to muscle with a homogenous enhancement. Tumor FDG-uptake in (18) F-FDG PET/CT scans is increased and might be a more accurate diagnostic tool [5, 6] than CT and MRI scans. Additionally the use of (18) F-FDG PET/CT scans is good choice in order to ensure its complete removal. This approach can necessary in multilobulated forms of ARM that complicate a total excision [5]. Fine-needle biopsies are a good method for pretherapeutic diagnosis [7].

mARM is a special group within ARM defined by multifocal appearance at the same time and should clearly separated from non-mARM. About 15% of the ARM-patients show additional lesions [8]. A systematic PubMed/MedLine, Cochrane Library, Google Scholar and Scopus search (time of search: 2018) with the key words ‘rhabdomyoma’, ‘multifocal rhabodmyoma’, ‘multilocular rhabdomyoma’ and ‘multicentric rhabdomyoma’ was performed. Double listing, double reporting, findings mentioned by de Trey et al. (2013), non case reporting articles, ARM reports outside head and neck region as well as CR, FRM and GRM were excluded from the results. All reports of ARM with a multilobulated but not multifocal nature were excluded as well.

Together with the case at hand, there were 22 case reports with 27 histologically confirmed ARM (Table 1). In summary, the patients suffered from 2 to 7 simultaneous (mean 2.5) lesions per patient. Mean age at diagnosis was 65 years (median 65) with a male to female ratio of 5.75:1. Common localizations were the parapharyngeal space (35%), larynx (14%), submandibular (13%), paratracheal region (14%), tongue (10%), floor of mouth (9%), neck (3%) as well as the soft palate (2%). Surgical excision was the first choice of treatment. There were also cases of successful laser excision of ARM but no longtime follow-up data was given [9]. In total, a recurrence rate of at least 27% was reported. This may be due to the multilobulated character of some ARM that are often connected by small strands of fibrous tissue to tumor lobules. Especially in those cases in toto removal may be difficult [10].

Table 1

Overview of all reported multifocal ARM cases since 1948.

Report numberAuthorYear of publicationAgeSexNumber of rhabdomyomaSideLocalization
1Beyer and Blair194852M2LFloor of mouth
LParapharyngeal space (hypopharynx)
2Goldmann196382M2LParapharyngeal space (sternohyoid muscle)
LLarynx (true vocal cord)
3Assor and Thomas196959M2LSubmandibular region
RParapharyngeal space
4Weitzel and Myers197656M3LParapharyngeal space
LParapharyngeal space
RParapharyngeal space
5Scrivner and Meyer198072M3RTongue (base of tongue)
LLarynx (vallecula)
RParapharyngeal space
6Neville and McConnel198158M2RFloor of mouth
LLarynx (supraglottis)
7Gardner and Corio198360M2LSubmandibular region
LLarynx (endolarynx (posterior wall of ventricle))
8Schlosnagle et al.198365F3LSubmandibular region
RSubmandibular region
Tongue (base of tongue)
9Golz198881M2RParatracheal region
Larynx (retrolaryngeal region)
10Berthoff et al.198865M2LFloor of mouth
LNeck
11Walker and Laszewski199076M3Tongue
RNeck
LParapharyngeal space
12Shemen et al.199253M4RParapharyngeal space
LFloor of mouth
RParatracheal region (retrothyroidal)
LLarynx
13Shemen et al.199275M2RFloor of mouth
RParapharyngeal space
14Kapadia et al.199359M2Larynx
Parapharyngeal space
15Fortson et al.199371M2RParapharyngeal space
RSubmandibular region
16Zbaren et al.199564M3RSubmandibular region
LLarynx (aryepiglottic fold)
RLarynx (aryepiglottic fold)
17Vermeersch et al.200066M2LParapharyngeal space
RParapharyngeal space
18Welzel et al.200177F2RParapharyngeal space
RParatracheal region
19Padilla Parrado et al.200569F2LParapharyngeal space
Paratracheal region (anterior mediastinum)
20Liess et al.200569M2RSubmandibular region
RLarynx (epiglottis)
21Delides et al.200559M2RTongue
RParatracheal region (retrothyroidal)
22Koutsimpelas et al.200872F2LLarynx (aryepiglottic fold)
RParatracheal region (proximal oseophagus/retrothyroidal)
23De Medts et al.200765M3RTongue (base of tongue)
RFloor of mouth
RSubmandibular region
24Grosheva et al.200845M2Parapharyngeal space (retropharyngeal space)
LParapharyngeal space
25Bizon et al.200865M3RParapharyngeal space
LTongue (base of tongue)
RSubmandibular region
26de Trey et al.201355M7LParapharyngeal space
RParapharyngeal space
RParapharyneal space (retropharyngeal space)
LParatracheal region
RParatracheal region
RFloor of mouth
LTongue (base of tongue)
27Present case201664M3RSoft palate
RParatracheal region (parathyroidal)
LParatracheal region (parathyroidal)
Report numberAuthorYear of publicationAgeSexNumber of rhabdomyomaSideLocalization
1Beyer and Blair194852M2LFloor of mouth
LParapharyngeal space (hypopharynx)
2Goldmann196382M2LParapharyngeal space (sternohyoid muscle)
LLarynx (true vocal cord)
3Assor and Thomas196959M2LSubmandibular region
RParapharyngeal space
4Weitzel and Myers197656M3LParapharyngeal space
LParapharyngeal space
RParapharyngeal space
5Scrivner and Meyer198072M3RTongue (base of tongue)
LLarynx (vallecula)
RParapharyngeal space
6Neville and McConnel198158M2RFloor of mouth
LLarynx (supraglottis)
7Gardner and Corio198360M2LSubmandibular region
LLarynx (endolarynx (posterior wall of ventricle))
8Schlosnagle et al.198365F3LSubmandibular region
RSubmandibular region
Tongue (base of tongue)
9Golz198881M2RParatracheal region
Larynx (retrolaryngeal region)
10Berthoff et al.198865M2LFloor of mouth
LNeck
11Walker and Laszewski199076M3Tongue
RNeck
LParapharyngeal space
12Shemen et al.199253M4RParapharyngeal space
LFloor of mouth
RParatracheal region (retrothyroidal)
LLarynx
13Shemen et al.199275M2RFloor of mouth
RParapharyngeal space
14Kapadia et al.199359M2Larynx
Parapharyngeal space
15Fortson et al.199371M2RParapharyngeal space
RSubmandibular region
16Zbaren et al.199564M3RSubmandibular region
LLarynx (aryepiglottic fold)
RLarynx (aryepiglottic fold)
17Vermeersch et al.200066M2LParapharyngeal space
RParapharyngeal space
18Welzel et al.200177F2RParapharyngeal space
RParatracheal region
19Padilla Parrado et al.200569F2LParapharyngeal space
Paratracheal region (anterior mediastinum)
20Liess et al.200569M2RSubmandibular region
RLarynx (epiglottis)
21Delides et al.200559M2RTongue
RParatracheal region (retrothyroidal)
22Koutsimpelas et al.200872F2LLarynx (aryepiglottic fold)
RParatracheal region (proximal oseophagus/retrothyroidal)
23De Medts et al.200765M3RTongue (base of tongue)
RFloor of mouth
RSubmandibular region
24Grosheva et al.200845M2Parapharyngeal space (retropharyngeal space)
LParapharyngeal space
25Bizon et al.200865M3RParapharyngeal space
LTongue (base of tongue)
RSubmandibular region
26de Trey et al.201355M7LParapharyngeal space
RParapharyngeal space
RParapharyneal space (retropharyngeal space)
LParatracheal region
RParatracheal region
RFloor of mouth
LTongue (base of tongue)
27Present case201664M3RSoft palate
RParatracheal region (parathyroidal)
LParatracheal region (parathyroidal)
Table 1

Overview of all reported multifocal ARM cases since 1948.

Report numberAuthorYear of publicationAgeSexNumber of rhabdomyomaSideLocalization
1Beyer and Blair194852M2LFloor of mouth
LParapharyngeal space (hypopharynx)
2Goldmann196382M2LParapharyngeal space (sternohyoid muscle)
LLarynx (true vocal cord)
3Assor and Thomas196959M2LSubmandibular region
RParapharyngeal space
4Weitzel and Myers197656M3LParapharyngeal space
LParapharyngeal space
RParapharyngeal space
5Scrivner and Meyer198072M3RTongue (base of tongue)
LLarynx (vallecula)
RParapharyngeal space
6Neville and McConnel198158M2RFloor of mouth
LLarynx (supraglottis)
7Gardner and Corio198360M2LSubmandibular region
LLarynx (endolarynx (posterior wall of ventricle))
8Schlosnagle et al.198365F3LSubmandibular region
RSubmandibular region
Tongue (base of tongue)
9Golz198881M2RParatracheal region
Larynx (retrolaryngeal region)
10Berthoff et al.198865M2LFloor of mouth
LNeck
11Walker and Laszewski199076M3Tongue
RNeck
LParapharyngeal space
12Shemen et al.199253M4RParapharyngeal space
LFloor of mouth
RParatracheal region (retrothyroidal)
LLarynx
13Shemen et al.199275M2RFloor of mouth
RParapharyngeal space
14Kapadia et al.199359M2Larynx
Parapharyngeal space
15Fortson et al.199371M2RParapharyngeal space
RSubmandibular region
16Zbaren et al.199564M3RSubmandibular region
LLarynx (aryepiglottic fold)
RLarynx (aryepiglottic fold)
17Vermeersch et al.200066M2LParapharyngeal space
RParapharyngeal space
18Welzel et al.200177F2RParapharyngeal space
RParatracheal region
19Padilla Parrado et al.200569F2LParapharyngeal space
Paratracheal region (anterior mediastinum)
20Liess et al.200569M2RSubmandibular region
RLarynx (epiglottis)
21Delides et al.200559M2RTongue
RParatracheal region (retrothyroidal)
22Koutsimpelas et al.200872F2LLarynx (aryepiglottic fold)
RParatracheal region (proximal oseophagus/retrothyroidal)
23De Medts et al.200765M3RTongue (base of tongue)
RFloor of mouth
RSubmandibular region
24Grosheva et al.200845M2Parapharyngeal space (retropharyngeal space)
LParapharyngeal space
25Bizon et al.200865M3RParapharyngeal space
LTongue (base of tongue)
RSubmandibular region
26de Trey et al.201355M7LParapharyngeal space
RParapharyngeal space
RParapharyneal space (retropharyngeal space)
LParatracheal region
RParatracheal region
RFloor of mouth
LTongue (base of tongue)
27Present case201664M3RSoft palate
RParatracheal region (parathyroidal)
LParatracheal region (parathyroidal)
Report numberAuthorYear of publicationAgeSexNumber of rhabdomyomaSideLocalization
1Beyer and Blair194852M2LFloor of mouth
LParapharyngeal space (hypopharynx)
2Goldmann196382M2LParapharyngeal space (sternohyoid muscle)
LLarynx (true vocal cord)
3Assor and Thomas196959M2LSubmandibular region
RParapharyngeal space
4Weitzel and Myers197656M3LParapharyngeal space
LParapharyngeal space
RParapharyngeal space
5Scrivner and Meyer198072M3RTongue (base of tongue)
LLarynx (vallecula)
RParapharyngeal space
6Neville and McConnel198158M2RFloor of mouth
LLarynx (supraglottis)
7Gardner and Corio198360M2LSubmandibular region
LLarynx (endolarynx (posterior wall of ventricle))
8Schlosnagle et al.198365F3LSubmandibular region
RSubmandibular region
Tongue (base of tongue)
9Golz198881M2RParatracheal region
Larynx (retrolaryngeal region)
10Berthoff et al.198865M2LFloor of mouth
LNeck
11Walker and Laszewski199076M3Tongue
RNeck
LParapharyngeal space
12Shemen et al.199253M4RParapharyngeal space
LFloor of mouth
RParatracheal region (retrothyroidal)
LLarynx
13Shemen et al.199275M2RFloor of mouth
RParapharyngeal space
14Kapadia et al.199359M2Larynx
Parapharyngeal space
15Fortson et al.199371M2RParapharyngeal space
RSubmandibular region
16Zbaren et al.199564M3RSubmandibular region
LLarynx (aryepiglottic fold)
RLarynx (aryepiglottic fold)
17Vermeersch et al.200066M2LParapharyngeal space
RParapharyngeal space
18Welzel et al.200177F2RParapharyngeal space
RParatracheal region
19Padilla Parrado et al.200569F2LParapharyngeal space
Paratracheal region (anterior mediastinum)
20Liess et al.200569M2RSubmandibular region
RLarynx (epiglottis)
21Delides et al.200559M2RTongue
RParatracheal region (retrothyroidal)
22Koutsimpelas et al.200872F2LLarynx (aryepiglottic fold)
RParatracheal region (proximal oseophagus/retrothyroidal)
23De Medts et al.200765M3RTongue (base of tongue)
RFloor of mouth
RSubmandibular region
24Grosheva et al.200845M2Parapharyngeal space (retropharyngeal space)
LParapharyngeal space
25Bizon et al.200865M3RParapharyngeal space
LTongue (base of tongue)
RSubmandibular region
26de Trey et al.201355M7LParapharyngeal space
RParapharyngeal space
RParapharyneal space (retropharyngeal space)
LParatracheal region
RParatracheal region
RFloor of mouth
LTongue (base of tongue)
27Present case201664M3RSoft palate
RParatracheal region (parathyroidal)
LParatracheal region (parathyroidal)

CONFLICT OF INTEREST STATEMENT

The authors declare that they have no conflict of interests.

FUNDING

This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.

AUTHORS’ CONTRIBUTIONS

M.D. and P.W.K. conducted the interpretation of the data, analyzed the data, did the statistics and drafted the manuscript. S.-K.K. did the histopathological analyses. All authors read and approved the final article.

ETHICAL APPROVAL

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

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