Two Cases of Meningothelial Hamartoma / 대한피부과학회지

Meningothelial hamartomas represent a collection of meningothelial elements in ectopic skin lesions. They present as a tan-gray, red, flesh-colored papule or nodule with alopecia on the scalp. Histologically, there are numerous thin-walled pseudovascular spaces lined by meningothelial cells with psammoma bodies and collagen bodies. The meningothelial cells are immunopositive for vimentin and epithelial membrane antigen (EMA). We report two cases of meningothelial hamartomas. A 16-year-old boy had a skin-colored nodule with alopecia on the midline of the occipital area. Histopathologic examination showed meningothelial cells in collagen fibers, and these cells formed pseudovascular spaces. Immunohistochemical staining was positive for EMA. Brain MRI showed no abnormality in skull or brain parenchyma. Our other patient was a 1-month-old girl who had a depressed alopecic plaque on the central line of the occipital area. Skin biopsy showed a pseudovascular space consisting of meningothelial cells, which were positive for EMA. There was no gross abnormality of the skull or brain parenchyma.

A Case of Rudimentary Meningocele / 대한피부과학회지

Rudimentary menigocele is a developmental anomaly in which menigothelial elements are present in the skin and subcutaneous tissue. A 9-year-old boy presented with a well-circumscribed, central atrophic and alopecic patch on the midline of the occipital area, and this lesion had been present at birth. Histological examination showed dense collagen bundles with pseudovascular spaces lined by oval, spindle shaped cells in the dermis and the subcutaneous layer. Collagen bodies and psammoma body were also detected. On the immunohistochemistry, these oval, spindle shaped cells were positive for vimentin, but negative for CD31, EMA and S100 protein.

A Case of Rudimentary Meningocele / 대한피부과학회지

Rudimentary meningocele, also known as a 'variant of primary cutaneous meningioma' or 'acoelic meningeal hamartoma', is an unusual developmental anomaly in which meningothelial elements are found in the skin. A 8-month-old girl has a well-circumscribed, alopecic, atrophic patch on the midline of the occipital area since birth. Histologically, pseudovascular spaces lined with flattened or cuboidal cells were seen in the papillary and upper reticular dermis without collagen bodies. These flattened or cuboidal cells were positive for vimentin, but negative for EMA, immunohistochemically. Radiographic finding of the scalp revealed no underlying bony defect.

A Case of Rudimentary Meningocele / 대한피부과학회지

Rudimentary meningocele is a variant of primary cutaneous meningioma and a very rare ectopic meningothelial hamartoma usually found in the subcutis. The prognosis is not so poor as long as it is not associated with major skeletal anomalies and intracranial communication through the bony defect. A 7-year-old male presented a normal-skin appearing, soft, indolent, slightly elevated nodule with alopecia on the vertex, measuring about 1.0X1.0X0.4cm. There was no physical or neurologic defect. The extracranial mass had no intracranial connection although minimal skull bone defect in the sagittal sinus was detected by the roentgenogram. The nodule was removed by excision and there has been no relapse during a period of one-year follow-up.

Two Cases of Rudimentary Meningocele / 대한피부과학회지

Rudimentary meningoceles represent a developmental anomaly in which meningothelial elements are found in the skin. The majority of rudimentary meningoceles occur on the scalp over the occiput or along cranial suture lines. They are present as a pink papule, nodule or an area of alopecia. Histologically, the lesion consists of scattered foci of meningothelial cells, an anastomosing network of empty spaces with psammoma bodies and collagen bodies, and small vessels, which may be located from the dermis to the subcutis. Immunohistochemically, the meningothelial cells are commonly positive for vimentin and often positive for EMA. We report the cases of two infants who were noted at birth to have scalp hair anomalies. One had a translucent, bald, slightly atrophic patch on the midline of the vertex and the other had a subcutaneous nodule surrounded by long hairs, so called "hair collar sign" on the midline of the occipital area. The latter had an underlying skull defect without a communication with intracranial spaces. Due to the occasional presence of connection to the central nervous system, any midline lesion in an infant, including rudimentary meningocele, deserves careful preoperative evaluation including imaging studies.