Rippled Pattern Sebaceoma | Dermatopathology

The findings are diagnostic of an exceedingly rare adnexal tumor namely the rippled pattern sebaceoma. This very uncommon tumor can be predominated by undifferentiated epithelial cells with only a minor mature sebocyte component, certainly a finding well-exemplified by this case. The rippled pattern sebaceoma is one of the classic primary epithelial tumors of the skin that can show a distinct Verocay body-like pattern that of course can lead to a misinterpretation of such lesions as a peripheral nerve sheath tumor especially if there is no epidermal continuity. Kimura et al. reviewed the clinicopathologic features of rippled pattern sebaceoma and found that it occurred predominantly on the scalp in men, whereas sebaceoma without rippled pattern occurred more frequently on the face of women. Sebaceomas without rippled pattern were frequently associated with an adjacent nevus sebaceous, seborrheic keratosis, and trichoblastoma; however, there were no such association in rippled-pattern sebaceoma. Reference: Ansai S, Kimura T. Rippled-pattern sebaceoma: a clinicopathological study. Am J Dermatopathol. 2009 Jun;31(4):364-6.

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Slide 1: 49 year-old man with an alar lesion. <br><br>The resection specimen is highly cellular composed of

Slide 2: These elongate basaloid appearing cells that have almost a fusiform appearance exhibiting a very distinct rippled growth pattern in a fashion that exactly recapitulates a Verocay body with the order of the parallel alignment of the elongate nuclei with the centrally disposed cytoplasmic processes. These rippled Verocay-like areas are interposed by intersecting plexiform fascicles of elongate fusiform spindled cells.

Slide 3: In examining the cells under higher magnification the nuclei are vesicular with indistinct nucleoli. The cytoplasms both in the rippled pseudo-Verocay body-like areas as well as in the more plexiform sheet-like intersecting foci are lightly eosinophilic. However there are occasional cells that do appear vacuolated with somewhat crinated nuclear outlines which at least histomorphologically defines a cytology that one associates with a mature sebocyte. This cell populace occupies less than 5% of the entire lesion.

Slide 4: There is extensive immunoreactivity of the neoplasm for P63. and the neoplasm is present in continuity with the epidermis.

Slide 5: The pan cytokeratin preparation is important in demonstrating that a significant component of this lesion does not exhibit immunoreactivity. The more rippled areas for example are negative while the plexiform sheet-like spindled foci are positive. The proliferation index was low (less than 10%).