Pediatric Lymphomatoid Papulosis "Type E" Exclusively Involving the Oral Mucosa: Case Report and Review of the Literature.

Lymphomatoid papulosis (LyP) type E is a rare form of primary cutaneous CD30 + lymphoproliferative disorder characterized by recurrent ulcerative lesions on the skin and/or mucous membranes, after a course of remissions and relapses; however, it is a localized disease with a good prognosis. We have previously reported 2 cases of LyP types C and D with exclusively intraoral involvement. To date, 32 cases of intraoral LyP have been reported. Of them, only 3 cases were diagnosed as LyP type E. We report a 17-year-old Mexican female patient who developed multiple intraoral lesions, without skin or other mucosal surface involvement, with episodes of remission and exacerbation. Histopathologic analysis revealed infiltrates of small-to-medium-sized atypical lymphoid cells, with foci of angiocentric and angioinvasive pattern. By immunohistochemistry, the atypical lymphoid cells were positive for CD3, CD5, CD7 (partial loss), and CD8. Unlike TCRD, TCRBF1 highlighted numerous atypical lymphoid cells, which were also CD30, granzyme B, perforin, TIA-1, and MUM1 positive, and whose angiocentric and angioinvasive pattern was evidenced through CD34 and α-SMA markers. EBER1/2 was negative, with Ki-67 highlighting most atypical lymphoid cells. Treatment with topical corticosteroids has provided considerable improvements, showing resolution of lesions. To the best of our knowledge, this is the first case of LyP type E affecting a pediatric patient with lesions confined to the oral mucosa.