Botryoid Rhabdomyosarcoma of the Conjunctiva in a Young Boy

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.

Molecular profile of head and neck rhabdomyosarcomas: A systematic review and meta-analysis

OBJECTIVE

This systematic review aimed to identify the molecular alterations of head and neck rhabdomyosarcomas (HNRMS) and their prognostic values.

STUDY DESIGN

An electronic search was performed using PubMed, Embase, Scopus, and Web of Science with a designed search strategy. Inclusion criteria comprised cases of primary HNRMS with an established histopathological diagnosis and molecular analysis. Forty-nine studies were included and were appraised for methodological quality using the Joanna Briggs Institute Critical Appraisal tools. Five studies were selected for meta-analysis.

RESULTS

HNRMS predominantly affects pediatric patients (44.4%), and the parameningeal region (57.7%) is the most common location. The alveolar variant (43.2%) predominates over the embryonal and spindle cell/sclerosing types, followed by the epithelioid and pleomorphic variants. PAX-FOXO1 fusion was observed in 103 cases of alveolar RMS (79.8%). MYOD1 mutation was found in 39 cases of sclerosing/spindle cell RMS (53.4%). FUS/EWSR1-TFCP2 gene fusions were identified in 21 cases of RMS with epithelioid and spindle cell morphologies (95.5%). The 5-year overall survival rate of patients was 61.3%, and MYOD1 mutation correlated with significantly higher mortality.

CONCLUSION

The genotypic profile of histologic variants of HNRMS is widely variable, and MYOD1 mutation could be a potential prognostic factor, but more studies are required to establish this.

Epibulbar Proliferative Fasciitis, a Variant of Nodular Fasciitis: A Differential Diagnosis of Conditions With Focal or Diffuse Myxoid Stromas

PURPOSE

To describe the clinical and pathologic features of a case of epibulbar proliferative fasciitis and to compare it with other focal or diffuse myxoid lesions.

METHODS

A clinical, histopathologic, and immunohistochemical analysis was performed. The clinical history, photographic documentation, history, and referred slides were reanalyzed. Additional immunohistochemical stains were performed at our institution.

RESULTS

A 68-year-old woman developed over a week a brightly vascularized and focally hemorrhagic placoid lesion on the temporal side of the OS. She had had earlier augmentation breast surgery that had been mistakenly initially reported to us to be for breast carcinoma. Hematoxylin- and eosin-stained reactions revealed microscopically a spindle cell lesion with an intact nonkeratinizing epithelium and a background myxoid stroma with prominent capillaries and a light dispersion of small T-cell lymphocytes. Most striking among the spindle cells were some widely separated large atypical cells. The atypical cells were cytokeratin positive, but an expansive panel of immunohistochemical stains for breast carcinoma was negative. The lesion was diagnosed as proliferative fasciitis and has not recurred after 1-year follow up.

CONCLUSION

A rapidly evolving conjunctival lesion is unlikely to be a primary or metastatic carcinoma. In the current case, the large ganglioform or rhabdomyoblast-like cells displayed diffuse cytokeratin positivity, still consistent with a mesenchymal or connective tissue cell lineage. Cytokeratin expression has been a finding previously reported in connective tissue tumors and in lymphoma cells. While the current lesion clinically resembles a conventional nodular fasciitis, the presence of the large atypical cells can lead to the misdiagnosis of a sarcoma, which typically displays a much higher Ki-67 proliferation index in comparison with nodular/proliferative fasciitis.

Primary Conjunctival Rhabdomyosarcoma in a Pediatric Patient

Rhabdomyosarcomas are neoplasms with a high degree of malignancy and arise from the embryonic mesenchyme. They represent approximately 5% of all pediatric tumors and their main locations are the head and neck (45%), trunk (40%), and extremities (15%). Twenty-five percent to 30% of the head and neck rhabdomyosarcomas appear in the orbit; however, its origin from the conjunctiva is rare, with few case reports published in the literature.

We present the case of a five-year-old girl with a diagnosis of primary embryonic rhabdomyosarcoma of the conjunctiva, treated with surgery and chemotherapy. After completing the treatment, it was followed up with controls for oncological ophthalmology, pediatric hematology-oncology, and radiotherapy oncology every six months with magnetic resonance of the orbits. Two years after the end of treatment, the patient is disease-free.

Conjunctiva rhabdomyosarcoma is a rare lesion, with few previously reported cases. In the reported case, the histopathological findings and positivity of the different immunohistochemical markers allowed a definitive diagnosis of rhabdomyosarcoma. The excellent prognosis of this pathology is probably linked to the early diagnosis of the disease and the timely administration of radical treatment.

It is essential to be able to identify conjunctival rhabdomyosarcoma from its clinical and histopathological characteristics in order to achieve early diagnosis and provide adequate treatment to patients.