Glomus tumor of Hoffa's fat pad and its management by arthroscopic excision.

We present a rare case of glomus tumor of Hoffa's fat pad in a 42-year-old woman. Magnetic resonance imaging findings along with the characteristic clinical picture led us to suspect a glomus tumor as the possible etiology. An ischemia test was found to be positive and this further substantiated our diagnosis. An arthroscopic excision was performed and the histology confirmed the diagnosis of glomus tumor of Hoffa's fat pad. The patient responded well to the excision with immediate complete resolution of pain and she remains asymptomatic at the last follow-up after 15 months. To our knowledge, this is the second reported case of glomus tumor of Hoffa's fat pad and the first ever to be managed by simple arthroscopic excision. The tumor poses a great challenge to an orthopedic surgeon. However, knowledge of its characteristic clinical presentation and the recognition of such a rare entity can help achieve an early diagnosis and timely management.

Reverse transcriptase-polymerase chain reaction as an ancillary molecular technique in the diagnosis of small blue round cell tumors by fine-needle aspiration cytology.

We evaluated the feasibility and usefulness of reverse transcriptase-polymerase chain reaction (RT-PCR) on fine-needle aspirates for categorization of small blue round cell tumors (SBRCTs). A total of 51 cases, including 25 Ewing sarcoma/peripheral primitive neuroectodermal tumors (PNETs), 11 rhabdomyosarcomas, 13 neuroblastomas, and 2 desmoplastic small round cell tumors (DSRCTs) were analyzed. The detection of the EWS-FLI1 (20/25) and EWS-ERG (4/25) fusion transcripts resolved 24 of 25 cases of Ewing sarcoma/PNET. The PAX3/7-FKHR fusion transcript was detected in 2 of 4 cases of alveolar rhabdomyosarcoma and the EWS-WT1 transcript in both cases of DSRCT. Tyrosine hydroxylase and 3,4-dihydroxyphenylalanine (dopa) decarboxylase transcripts were demonstrated in 10 of 13 cases of neuroblastoma. In comparison, immunocytochemical analysis resolved 19 (76%) of 25 Ewing sarcomas, 9 (82%) of 11 rhabdomyosarcomas, 6 (46%) of 13 neuroblastomas, and 1 (50%) of 2 DSRCTs. Overall, RT-PCR resolved 38 (86%) of 44 vs 35 (69%) of 51 cases by immunocytochemical analysis. RT-PCR is easily applied to fine-needle aspirates of SBRCT and greatly facilitates accurate tumor typing.