A Benign Cutaneous Plexiform Hybrid Tumor of Perineurioma and Cellular Neurothekeoma

Abstract

There are several recent reports describing hybrid peripheral nerve sheath tumors showing a biphasic component of neoplastic cells. These combinations include a mixture of neurofibroma and schwannoma, schwannoma and perineurioma, neurofibroma and perineurioma, and perineurioma and granular cell tumor. A case of a triphasic combination of neurofibroma, schwannoma, and perineurioma has also been described. We describe the clinicopathologic and immunohistochemical characteristics of 9 cases of a benign cutaneous plexiform nerve sheath tumor located on the lips and exhibiting hybrid features of perineurioma and cellular neurothekeoma. Clinically, lesions were solitary dome-shaped papules located on the lips. Histopathologically, the neoplasms consisted of well-circumscribed but uncapsulated dermal nodules with a plexiform pattern. They were composed of nests or rounded aggregations of neoplastic cells embedded in a slightly myxoid stroma. Within the aggregates, cells were distributed in a storiform and lamellar pattern. Immunohistochemically, most neoplastic cells expressed strong immunoreactivity for S100A6, MiTF, NKI/C3, PGP9.5, EMA, and NSE, whereas variable, focal, and weaker positivity for CD34, claudin-1, and Glut-1 was seen in some cases. On the basis of these findings, we believe that this neoplasm is a distinctive benign cutaneous plexiform nerve sheath tumor with histopathologic and immunohistochemical hybrid features of perineurioma and cellular neurothekeoma.

Hybrid peripheral nerve sheath tumors: report of five cases and detailed review of literature

“…The patient was a 24-year-old female with an internal auditory canal mass. The same year, Requena et al [29] published a series of 9 hybrid PNSTs, all located on the lips and histologically showing distinct features of perineurioma and cellular neurothekeoma. Hayashi et al reported multifocal intradural tumors at T11/12 and L1 in a 63-year-old-male.…”

“…All were histologically consistent with hybrid schwannoma/perineurioma, had features of high cellularity, nuclear atypia and raised proliferative index which recurred five months after surgical resection as an intraneural perineurioma, showing mitotic activity and proliferative index even higher than that seen in the primary hybrid tumors [30]. Following Requena et al [29] in 2013, Yamada et al [31] reported a hybrid perineurioma and cellular neurothekeoma arising in the nose (unlike Requena’s nine cases, all of which were located in the lips). In 2013, which was indeed a very dynamic year for publication of reports and series of hybrid PNSTs, Kacerovska et al [10] published a series of five cases occurring in the setting of NF Type 1.…”

Benign cutaneous plexiform hybrid tumor of perineurioma and cellular neurothekeoma arising from the nose

“…There have been several interesting reports describing hybrid peripheral nerve sheath tumors comprising of biphasic (i.e., hybrid) features of neoplastic cells, as follows: a mixture of neurofibroma and schwannoma; schwannoma and perineurioma; perineurioma and granular cell tumor; and so on [1-4]. More recently, Requena et al showed the detailed clinicopathological features of 9 cases of a benign cutaneous plexiform nerve sheath tumor with hybrid characteristics of perineurioma and cellular neurothekeoma, given the name as a benign cutaneous plexiform hybrid tumor of perineurioma and cellular neurothekeoma ( HPN ), all of which were peculiarly located on the lips [1].…”

“…More recently, Requena et al showed the detailed clinicopathological features of 9 cases of a benign cutaneous plexiform nerve sheath tumor with hybrid characteristics of perineurioma and cellular neurothekeoma, given the name as a benign cutaneous plexiform hybrid tumor of perineurioma and cellular neurothekeoma ( HPN ), all of which were peculiarly located on the lips [1]. Herein we reported an extremely rare and first case of HPN of the nose occupying the dermis to superficial subcutis as a well-demarcated nodule.…”

“…Our case unusually occurred in the nose, but not the lip. Actually, Requena et al have reported that HPN seems to have a special predilection for perioral skin, however, its etiology remains to be elucidated [1]. All pathologists should be aware that its histologically, rather than clinically, characteristic findings from extensively careful immunohistochemical examination can induce one of differential diagnoses, and possibly a correct diagnosis.…”