Potentially useful markers for desmoplastic melanoma: an analysis of KBA.62, p-AKT, and ezrin.

Desmoplastic melanoma (DM) represents only a small portion of newly diagnosed melanoma cases but can be a significant diagnostic challenge for dermatopathologists. Immunohistochemical stains are often useful to confirm the diagnosis; however, DM is notorious for not expressing most of the melanocytic markers other than S100. Recent studies have suggested several new markers, which may be promising in the diagnosis of DM. KBA.62 is a relatively new antimelanoma monoclonal antibody, which has not been well characterized in DM. Ezrin and p-Akt are additional markers, which have been shown to be involved in cell survival and proliferation. We collected 12 cases of DM and 18 cases of other lesions that could be included in the differential diagnosis. The H&E sections were reviewed, and immunohistochemical stains for KBA.62, p-AKT, and Ezrin were performed. Seventy-five percent of the DM cases (9 of 12) demonstrated positive staining (>5% of tumor cells staining) with KBA.62, with an average of 39% of cells staining. One hundred percent of the DM cases (12 of 12) demonstrated positive staining with Ezrin, with an average of 49% of tumor cells staining. Seventy-five percent of the DM cases (9 of 12) demonstrated positive staining with p-Akt, with an average of 49% of cells staining. KBA.62 and Ezrin demonstrated statistically significant increased staining of DM cases compared with the other lesions (P = 0.05 and P = 0.007, respectively), although it was not useful in distinguishing DM versus malignant peripheral nerve sheath tumor, whereas p-Akt showed no significant differences in staining between DM and the other cases. These findings suggest that KBA.62 may be a useful marker in confirming the diagnosis of DM.

Unusual palisading and necrotizing granulomas associated with a lubricating agent used in lipoplasty.

Palisading granulomas with necrobiosis are frequently encountered in dermatopathology, with granuloma annulare, necrobiosis lipoidica diabeticorum, and rheumatoid nodule being the most frequently rendered diagnoses. We report a series of 9 patients who developed palisading, necrobiotic, and necrotizing granulomas, associated with the presence of foreign material introduced through the use of a lubricating agent containing a copolymer (Carbopol 934) for liposuction. The patients ranged in age from 29 to 54 years old and presented with multiple, disfiguring, and nonhealing wounds at sites where lipoplasty had been performed. All specimens showed similar histologic findings, with the formation of palisading granulomas around extensive areas of necrobiosis with foci of true necrosis. Spaces containing minute fragments of crystalloid-appearing foreign material, birefringent with polarized light, were also identified. Special stains including acid fast, Gram, Giemsa, and/or periodic acid-Schiff were negative for organisms in all cases, as were cultures performed in 5 cases. Given the presence of foreign material and true necrosis, these findings were inconsistent with granuloma annulare, necrobiosis lipoidica diabeticorum, or rheumatoid nodule and were interpreted as a unique reaction to the foreign material. Therefore, this seems to be a distinct reaction pattern that has not been previously reported in the literature and may be important to include in the differential diagnosis in patients with necrotizing granulomatous disease.