Laryngeal botryoid rhabdomyosarcoma in an adult. Report of a case with electron microscopic study

Botryoid-type Embryonal Rhabdomyosarcoma: A Comprehensive Clinicopathologic and Molecular Appraisal With Cross-comparison to its Conventional-type Counterpart

Embryonal rhabdomyosarcoma (ERMS) is the most common subtype of RMS, occurring in soft tissue and visceral sites of young children, and is associated with favorable outcomes. A subset occurs in mucosal-lined luminal structures, displaying a unique grape-like growth termed as "botryoid-type." To further delineate the differences between conventional (cERMS) and botryoid-type (bERMS) RMS, we performed a comparative histologic review and comprehensive molecular profiling of 48 cases (25 bERMS and 23 cERMS). All tumors were subjected to a hybridization capture-based targeted matched tumor-normal DNA NGS assay. The mean age was 17 and 7 years for bERMS and cERMS, respectively. Most bERMS were female with a predilection for the gynecologic tract (75%), while cERMS had a slight male predominance and were preferentially located in abdominopelvic and paratesticular sites (30%, each). All bERMS exhibited an exophytic, bulbous architecture accompanied by a subepithelial "cambium layer." Distinctive germline alterations were detected, with DICER1 (18%) and FH (6%) mutations only in bERMS, and rare TP53, VHL, and APC mutations in cERMS. Similarly, contrasting somatic genomic landscapes were observed, with frequent DICER1 (52%, P**<0.0001) and TP53 (36%, P*<0.05) alterations exclusively in bERMS. Cartilaginous differentiation was only observed in DICER1-mutated bERMS. All patients had longitudinal follow-up. bERMS patients with somatic/germline DICER1 mutations showed significantly improved recurrence-free survival compared with that of DICER1-wild type patients (P*<0.05). Moreover, bERMS showed improved disease-specific survival compared with that of cERMS, with 8% versus 30% (P*<0.05) dead of disease, respectively. In summary, we compare the molecular underpinnings of the largest cohort of bERMS and cERMS with targeted DNA sequencing and long-term follow-up data. Our findings reveal divergent genomic topographies between the 2 groups, with bERMS showing unique germline and somatic abnormalities, including enrichment in DICER1 and TP53 alterations, and a trend towards improved survival.

Adult laryngeal Embryonal Rhabdomyosarcoma: a case report and literature review

Background

Laryngeal rhabdomyosarcomas (RMSs) mainly occurred in children, while were extremely rare in adults. Consequently, less information was available to guide clinicians to manage adult RMSs in larynx.

Case presentation

A 42-year-old man presented with a 2-year history of gradually worsening hoarseness. Then, he underwent a surgery with suspension laryngoscope with initially being diagnosed as vocal cord cyst. Unexpectedly, the lesion was proved to be embryonal rhabdomyosarcoma (ERMS), pathologically. Next, he underwent chemoradiotherapy, while the tumor relapsed 18 months after the last treatment. Subsequently, a vertical hemilaryngectomy and a right selective neck dissection was performed, and the chemotherapy according to the anticancer drug sensitivity in vitro was arranged. Until the last check-up 18 months after chemotherapy, the patient did not display clinical or radiological signs of local recurrence and metastases.

Conclusions

Misdiagnosis and missed diagnosis of laryngeal RMSs might appear when tumors presented as smooth protuberance. We reported the first case of laryngeal RMSs in an adult with the multidisciplinary strategy based on the chemosensitivity assay in vitro. Furthermore, a systematic review of the literature was also discussed, highlighting the initial diagnostic pitfalls and subsequent management problems that may occur with this uncommon tumor.

Pediatric-type sarcomas in adult patients

Sarcomas included in the broad group of small round-cell tumors (SRCT) and some non-SRCT lesions that typically are seen in pediatric-age patients can rarely occur in adults. However, there are differences in the anatomic sites that are involved and the prognosis in these two patient groups. The diagnosis of pediatric-type sarcomas in adults is often challenging because of the unusual contextual clinical setting and morphologic features. Immunohistochemical studies have greatly facilitated this process. Moreover, limited biomolecular studies that have been conducted have demonstrated comparable cytogenetic alterations in adults and children with pediatric-type tumors. They also have raised interesting questions concerning possible biological bases for differences in clinical behavior in the two cohorts. This review focuses on the morphological, immunohistochemical, and molecular characteristics of childhood-type sarcomas that affect adults, with emphasis on possible pitfalls in differential diagnosis.

Embryonal "Botryoid" rhabdomyosarcoma of the larynx: a clinicopathologic and immunohistochemical study of two cases

Two cases of embryonal rhabdomyosarcoma of the larynx are reported. The tumors occurred in a 16-year-old boy and in a 66-year-old man. They manifested clinically with nonspecific symptoms, including voice hoarseness and sense of throat fullness. Treatment consisted of total and partial laryngectomy, respectively. Grossly, both lesions had an exophytic growth pattern and microscopically featured a proliferation of small round to oval cells. Cell cytoplasms were occasionally stainable and fibrillary. Quite often, tumor cellularity was denser beneath the covering mucosa, recalling a "cambium layer" pattern. Tumor cells immunoreacted for desmin, actins, myoglobin, and sarcomeric actin; no immunostaining was noted for epithelial markers. No further antitumoral treatment was administered after surgery. There has been no recurrence of tumor at 2 and 10 years, respectively. Based on our series and the available literature, it seems that rhabdomyosarcoma of the larynx pursues a less-aggressive course than that seen in the homonimic juvenile or adult soft tissue lesion. Surgery alone appears to be a valid treatment option, especially when a polypoid, or "botryoid" gross pattern, coupled with the embryonal small cell histotype is encountered. In light of these findings, it is suggested that botryoid rhabdomyosarcoma of the larynx may deserve a specific consideration among the various laryngeal mesenchymal malignancies.

Juvenile (embryonal and alveolar) rhabdomyosarcoma of the head and neck in adults. A clinical, pathologic, and immunohistochemical study of 12 cases

Sites in the head and neck region (orbit, nasopharynx, nasal cavity, etc.) are among the most frequent locations for juvenile (embryonal and alveolar) rhabdomyosarcomas in patients younger than 15 years; however, comparable neoplasms in adults are very uncommon. A clinicopathologic and immunohistochemical study of 12 juvenile rhabdomyosarcomas in patients between the ages of 18 and 36 years is presented. There was a female:male ratio of 2:1. The orbit with or without contiguous paranasal sinus involvement, nasal cavity, sphenoid sinus, middle ear, and soft tissues of the neck and preauricular region were the primary sites. Seven tumors involved a parameningeal site and eight cases were alveolar rhabdomyosarcomas which together contributed to the adverse outcome. Only two patients were long-term, disease-free survivors. Six patients have died of tumor and two others are alive with persistent disease. Immunohistochemical study in 11 cases demonstrated reactivity for vimentin and muscle-specific actin (HHF-35) and desmin in ten cases. Juvenile rhabdomyosarcoma rarely presents in the head and neck of adults but should be considered in the differential diagnosis of a small cell neoplasm in patients during the third and fourth decades of life.