Primary Cutaneous Meningioma on the Scalp: Report of Two Siblings

Abstract

Primary cutaneous meningioma (PCM) is a rare tumor whose pathogenesis is quite obscure. We reported PCMs occurring on almost the same occipital region of two siblings studied by histology, immunohistochemistry, and electron microscopy. Both lesions were attached to duras, but extracranial. One lesion was histologically diagnosed as meningothelial meningioma; its tumor cells showed electron microscopically interdigitating cytoplasmic processes with junctional complexes. The other was interpreted as fibroblastic meningioma; its tumor cells were arranged linearly in a stepping-stone arrangement and had small dense bodies in the cytoplasm. The tumor cells stained positively with anti-vimentin antibody. Both lesions had adenomatous hyperplasia of the eccrine glands. Although the histologic and electron microscopic features of these two lesions slightly differed from each other, their pathogenesis was essentially considered to be acoelic or rudimentary meningocele.

Rudimentary Meningocele: Remnant of a Neural Tube Defect?

“…16,17 Myxoid stroma noted in either case may further obscure the diagnosis. [18][19][20] Immunoperoxidase staining is vital in distinguishing these disorders, as dermatofibrosarcoma protuberans typically expresses CD34 and fails to express EMA, while rudimentary meningoceles display opposite reactivity. 16 Although EMA expression is vital to the identification of cells of meningothelial lineage, it is important to note that EMA failed to label the network of pseudovascular spaces located in the superficial dermis in 3 of our patients.…”

Primary Ear and Temporal Bone Meningiomas: A Clinicopathologic Study of 36 Cases with a Review of the Literature

“…However, when the scalp, orbit, sinonasal tract, oral cavity, and soft tissues are excluded, the incidence decreases to Ͻ1% (9,35,36,46,51,55,(57)(58)(59). Primary ear and temporal bone meningiomas made up only 2.0% of the benign or malignant primary ear and temporal bone tumors seen in consultation at the AFIP during the period of study.…”

“…Increasing evidence supports the development of meningiomas from arachnoid cap cells, with different mechanisms to suggest how extracranial meningiomas arise. In the ear or mastoid bone specifically, an intracranial meningioma can extend by the path of least resistance and follow the tegmen tympani (through dehiscence), the sulci of the greater and lesser superficial petrosal nerves, the posterior fossa plate (geniculate ganglion area), the internal auditory canal (porus internus, lateral semicircular canal, or perilabyrinthine cell tracts), or the jugular foramen by direction extension, origination from arachnoid cell clusters in the sheaths of cranial nerves or vessels as they exit foramina or suture lines of the skull, or without any apparent demonstrable connection to the CNS (8,10,12,18,23,27,31,35,39,(45)(46)(47)(48)(49)(50)(51)(52)(53)(54)(55)(56). Arachnoid cells are identified outside the neuraxis, thereby giving rise to meningiomas in the ear and temporal bone.…”

Cutaneous Meningioma

“…The authors described this tumor as consisting of intimately associated cells that contained complicated interdigitating processes, desmosomes, and hemidesmosomes, thus creating a jigsaw pattern. Another study 11 described the findings from 2 cases. The first showed swollen and stellate meningothelial cells with round and oval nuclei, cytoplasm with a moderate number of microfilaments, straight and interdigitating cytomembranes, and desmosome-like junctions between cells.…”

“…5,11,22,24 One study 22 evaluated a cutaneous meningioma by electron microscopy in a 32-year-old man with a congenital lesion. The authors described this tumor as consisting of intimately associated cells that contained complicated interdigitating processes, desmosomes, and hemidesmosomes, thus creating a jigsaw pattern.…”