[1213] Use of Classic and Novel Immunohistochemical Markers in the Diagnosis of Cutaneous Myeloid Sarcoma.

Catalina Amador-Ortiz, Maria Y Hurley, Grant K Ghahramani, Stephanie Frisch, Klco M Jeffery, Anne C Lind, Tu-Dung Nguyen, Anjum Hassan, Friederike H Kreisel, John L Frater. Washington University, St. Louis, MO; St. Louis University, MO

Background: Although immunohistochemistry (IHC) can aid in the diagnosis of cutaneous myeloid sarcoma (CMS), specific markers have not been clearly identified. The purpose of this multi-institutional study was to evaluate the utility of classic and novel IHC markers in the diagnosis of CMS.
Design: 57 cases of CMS were used (24 females; 33 males, mean age: 50 years; range 3 months-88 years). We included 46 AML cases (3 M0, 5 M1, 6 M2, 11 M4, 11 M5, 1 M7, 1 biphenotypic, 2 with 11q23 [MLL] abnormalities, 6 unclassified), 6 myelodysplastic syndromes and 5 myeloproliferative disorders. Skin biopsy preceded bone marrow diagnosis in 3 cases, was concurrent in 16, and succeeded it in 38 cases. IHC was performed for CD14, CD33, CD34, CD117, CD163, myeloperoxidase (MPX), lysozyme, and Kruppel-like factor 4, monocyte-associated (KLF4).
Results: No significant differences were seen regarding location, pattern or intensity of leukemic infiltrate among the different leukemia subtypes. Lysozyme was expressed in 52 (91%), CD33 in 34 (60%), MPX in 31 (54%), CD34 in 22 (39%) and CD117 in 20 cases (35%). The monocytic markers CD14, KLF4, and CD163 were expressed in 34 (60%), 23 (40%) and 33 (58%) cases, respectively. Regardless of AML subtype, a panel of antibodies that included lysozyme, CD117, CD33, and CD34 identified all cases. CD14 and KLF4 expression were significantly more common in cases with monocytic differentiation, compared to cases with no monocytic component (80% vs. 20%, p<0.001 and 52% vs. 20%, p<0.05, respectively). The sensitivity, specificity, NPV, and PPV for monocytic markers in monocytic related AML cases were 80%, 80%, 87%, and 71% for CD14, 52%, 80%, 81%, and 50% for KLF4, and 64%, 47%, 67%, and 44% for CD163, respectively. The combination of CD14 and KLF4 detected the same proportion of monocytic related AML cases (84%) as when all three monocytic markers were used. The sensitivity and specificity for both markers combined was 88% and 67%, respectively.
Conclusions: In addition to classical IHC markers, targeted use of novel markers is useful in the diagnosis of CMS. CD33 enhances the detection of myelomonocytic differentiation. Of the monocytic markers, CD14 is the single most sensitive and specific marker for monocytic differentiation. While in isolation KLF4 is relatively insensitive, it enhances sensitivity in detecting monocytic CMS when combined with CD14. This combination may be of use in confirming monocytic differentiation.
Category: Hematopathology

Monday, February 28, 2011 1:00 PM

Poster Session II # 192, Monday Afternoon


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