Pathologic quiz case: Ovarian mass in a 2-year-old girl presenting with pleural effusions

Alveolar rhabdomyosarcomas involving serous cavity fluid specimens exhibit diverse cytomorphologies: A case report and review of the literature

Involvement of serous cavity specimens by alveolar rhabdomyosarcoma (ARMS) is a rare event and only a few case reports have been reported in the literature, with conflicting cytomorphologic patterns. Herein, we report on a 41-year-old man with no significant past medical history who presented with pancytopenia and shortness of breath and was found to have widely metastatic sinonasal alveolar rhabdomyosarcoma, including involvement of the pleura. The pleural fluid specimen was cellular and contained ARMS cells in small-to-medium sized three-dimensional fragments that resembled an adenocarcinoma or mesothelioma, and numerous single cells were seen in the background. The individual tumor cells demonstrated variable morphology; all were large, with varying degree of cytoplasm, and multinucleated cells were commonly seen in the background. The cells were negative for calretinin and claudin-4 and were positive for myogenin, confirming the diagnosis. Given the cytomorphologic diversity of ARMS seen in serous fluid specimens, patient history and the use of confirmatory immunostains are essential.

FOXO1-FGFR1 fusion and amplification in a solid variant of alveolar rhabdomyosarcoma

Rhabdomyosarcoma is the most common pediatric soft tissue malignancy. Two major subtypes, alveolar rhabdomyosarcoma and embryonal rhabdomyosarcoma, constitute 20 and 60% of all cases, respectively. Approximately 80% of alveolar rhabdomyosarcoma carry two signature chromosomal translocations, t(2;13)(q35;q14) resulting in PAX3-FOXO1 fusion, and t(1;13)(p36;q14) resulting in PAX7-FOXO1 fusion. Whether the remaining cases are truly negative for gene fusion has been questioned. We are reporting the case of a 9-month-old girl with a metastatic neck mass diagnosed histologically as solid variant alveolar rhabdomyosarcoma. Chromosome analysis showed a t(8;13;9)(p11.2;q14;9q32) three-way translocation as the sole clonal aberration. Fluorescent in situ hybridization (FISH) demonstrated a rearrangement at the FOXO1 locus and an amplification of its centromeric region. Single-nucleotide polymorphism-based microarray analysis illustrated a co-amplification of the FOXO1 gene at 13q14 and the FGFR1 gene at 8p12p11.2, suggesting formation and amplification of a chimerical FOXO1-FGFR1 gene. This is the first report to identify a novel fusion partner FGFR1 for the known anchor gene FOXO1 in alveolar rhabdomyosarcoma.

Primary ovarian rhabdomosarcoma

Rhabdomyosarcoma (RMS) is usually considered a childhood soft tissue tumour. It normally arises within extremities, head and neck region and the genitourinary system. Common sites in the genitourinary tract include the urinary bladder, prostate and paratesticular soft tissues. It can arise at unusual sites but very rarely. RMS is more common in males as compared to females and two-thirds of the cases are diagnosed in children aged 6 years or younger with a smaller incidence peak in mid-adolescence. The annual incidence is four to seven per million children of 20 years or younger. Approximately 350 cases are diagnosed per year in the USA. Unfortunately, statistics of RMS are not known for Pakistan.

Solid variant of alveolar rhabdomyosarcoma mimicking non-Hodgkin lymphoma: case report and review of literature

Alveolar rhabdomyosarcoma is a high-grade neoplasm, which forms about 30% of rhabdomyosarcomas. A rare solid variant has been described. A 14-year-old girl presented with inguinal lymph nodal mass and was treated with 6 cycles of CHOP chemotherapy and local radiation. After 3 months, she presented with generalized lymphadenopathy, pleural and pericardial effusions. A histopathologic diagnosis of solid variant of alveolar rhabdomyosarcoma was made. The skeletal muscle origin was confirmed by positive immunostaining for desmin. A primary site was identified in the lower limb muscles. The patient was treated with salvage chemotherapy but had progressive disease. The pediatric and adolescent cases of this rare tumor reported in English language literature are reviewed. In addition, the importance of biopsy in the diagnosis of suspected lymphomas and the pitfalls of needle aspirations are briefly discussed.