Brain Pathology Case of the Month - December 2018


FINAL DIAGNOSIS

Meningioma with iron-positive macrophages (pseudo-pigmentation)

DISCUSSION

Macrophage reaction with iron-deposits is a common reaction to all vascularized nervous system pathologies, including tumors. Most of the times, the nature of these deposits is easily diagnosed by performing an iron stain. However, in selected cases, and basically at histomorphology grounds, the early differentiation from melanin deposits may be difficult, either, among a few causes, because the pigment may be found far from the vessels or because the tumor appearance respects one of those with melanin deposits. Indeed, deposition of melanin may occur in circumscribed tumors of the nervous system, the so-called pigmented tumors. These well-known entities may encompass metastatic melanoma, the most frequent by far, pigmented schwannomas, melanotic medulloblastomas, pigmented glial/ependymal and choroid plexus tumors, melanotic neuro-ectodermal tumors of infancy, and teratomas (1). However, if one considers the meninges pigmented-related neoplasms, the primary melanoma and the meningeal melanocytoma must be added. These tumors are thought to arise from leptomeningeal melanocytes neural crest derive (1), and they should display reaction with the anti-melanosomal antibodies HMB/45 and Melan A, and S100 (4).

The histomorphology of this tumor very much suggests a meningeal melanocytoma, i.e., fusiform/shaped arranged in sheets and in nests cells and without anaplasia. Melanocytomas are extremely rare and they may occur anywhere in the cranial and spinal meninges, approximately two thirds arising in the intracranial compartment (4). Furthermore, no typical histomorphological features suggesting a meningioma was elicited in the studied samples whatsoever. However, immunohistochemistry data strongly favours this diagnostic. Indeed, the vast majority of meningiomas stain for EMA and vimentin, and progesterone receptor reactivity may also be of help (4). Besides, MRI data also suggested a meningioma (2).

Colonization of non-pigmented tumors by pigmented melanocytes has been reported in extracranial neoplasms tumors occurring in several places of the body. Specifically, one case of melanocytic colonization of a meningioma confirmed by immunohistochemistry, ultrastructural analysis and molecular genetic has been described (3). This tumor should be considered a meningioma with iron-positive macrophages on immunohistochemistry and conventional histomorphology staining grounds, respectively, and also stresses the still value of ancient stains for the diagnosis of particular aspects of nervous system tumors.

REFERENCES

  1. Küsters-Vandevelde HVN, Küsters B, van Eugen-van Grunsven ACH, Groenen PJTA, Wesseling P, Blokx WAM (2015) Primary melanocytic tumors of the central nervous system: a review with focus on molecular aspects. Brain Pathology 25:209-226.
  2. Lee JK, Rho YJ, Jeong DM, Rhim SC, Kim SJ (2017) Diagnostic clue of meningeal melanocytomas: case report and review of literature. Yonsei Med J 58:467-470.
  3. Nestor SL, Perry A, Kurtkaya O, Abell-Aleff P, Rosemblat AM, Burger PC, et al (2003) Melanocytic colonization of a meningothelial meningioma: histopathological and ultrastructural findings with immunohistochemistry and genetic correlation: case report. Neurosurgery 53:211-215.
  4. Perry A, Louis DN, Budka H, von Deimling A, Sahm F, Rushing EJ, Mawrin C, Claus EB, Loeffler L, Sadetzki S (2016) Meningioma. In: WHO Classification of Tumours of the Central Nervous System. Louis NL, Ohgaki H, Wiestler OD, Cavenee WK (eds), Lyon, pp 231-245.

Contributed by José Pimentel, MD, PhD, Ana Afonso, MD, Rafael Roque, MD, João Paulo Farias, MD


International Society of Neuropathology