Comparative evaluation of flow-cytometric immunophenotyping and immunocytochemistry in the categorization of malignant small round cell tumors in fine-needle aspiration cytologic specimens.
BACKGROUND
The precise diagnosis of malignant small round cell tumors (MSRCTs) in fine-needle aspiration (FNA) cytology is a challenge that requires ancillary investigations. In this study, the authors evaluated the applicability of flow-cytometric immunophenotyping (FCI) and compared it with immunocytochemistry (ICC) for the accurate categorization of MSRCTs.


METHODS
In total, 37 consecutive MSRCTs that had been diagnosed with FNA cytology were analyzed by ICC and FCI using a panel of antibodies against desmin, vimentin, CD99/major histocompatibility class I-related antigen 2, neuron-specific enolase, and pancytokeratin. The final diagnoses included Ewing sarcoma (n = 17), rhabdomyosarcoma (n = 6; 4 embryonal and 2 alveolar subtypes), neuroblastoma (n = 10), desmoplastic small round cell tumor (n = 2), and retinoblastoma (n = 2).


RESULTS
Accurate categorization was possible in 67.5% of cases by ICC and in 64.8% of cases by FCI. Concordant immunophenotyping results with either technique were obtained in 21 cases (59.4%). Low cellularity of the sample and negativity for all markers tested were some limitations to both techniques when applied on fine-needle aspirates. However, using a combination of both techniques, 86.4% (32 of 37 cases) MSRCTs were typed accurately.


CONCLUSIONS
FCI is applicable on FNA material and complements ICC in accurate the typing of MSRCTs. This is particularly useful in advanced-stage disease, when neoadjuvant chemotherapy may be instituted promptly.
Gautam
Upasana
U
Department of Cytology and Gynecological Pathology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
Srinivasan
Radhika
R
Rajwanshi
Arvind
A
Bansal
Deepak
D
Marwaha
Ram Kumar
RK
D000071443:12E7 Antigen; D015703:Antigens, CD / Q000032:analysis; D001707:Biopsy, Needle / Q000379:methods*; D015815:Cell Adhesion Molecules / Q000032:analysis; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D007150:Immunohistochemistry; D016130:Immunophenotyping; D009447:Neuroblastoma / Q000737:chemistry / Q000276:immunology / Q000473:pathology*; D011446:Prospective Studies; D012208:Rhabdomyosarcoma / Q000737:chemistry / Q000276:immunology / Q000473:pathology*; D012512:Sarcoma, Ewing / Q000737:chemistry / Q000276:immunology / Q000473:pathology*
D000071443:12E7 Antigen; D015703:Antigens, CD; C061828:CD99 protein, human; D015815:Cell Adhesion Molecules