Annals of Indian Academy of Neurology
RESIDENTS CORNER
Year
: 2015  |  Volume : 18  |  Issue : 1  |  Page : 117--119

Atypical lytic lesions of skull: Clinical and radiological correlation


Sureka Binit, Mahesh Kumar Mittal, Aliza Mittal, Brij Bhushan Thukral 
 Department of Radiodiagnosis, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi, India

Correspondence Address:
Sureka Binit
Department of Radiodiagnosis, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi - 110 029
India

Abstract

Imaging alone cannot differentiate various isolated atypical lytic lesions involving the skull. Clinical and radiological correlation is mandatory in reaching to a diagnosis. Histopathology remains the gold standard. We describe few atypical cases presenting as isolated lytic lesions of skull with characteristic imaging findings and a brief clinical approach to reach towards the diagnosis.



How to cite this article:
Binit S, Mittal MK, Mittal A, Thukral BB. Atypical lytic lesions of skull: Clinical and radiological correlation.Ann Indian Acad Neurol 2015;18:117-119


How to cite this URL:
Binit S, Mittal MK, Mittal A, Thukral BB. Atypical lytic lesions of skull: Clinical and radiological correlation. Ann Indian Acad Neurol [serial online] 2015 [cited 2019 Dec 11 ];18:117-119
Available from: http://www.annalsofian.org/text.asp?2015/18/1/117/144309


Full Text

 Introduction



Skull or the calvarium encases the brain parenchyma. It consists of an inner table, outer table and the space between the two layers is known as diploe. The thicknesses of outer and inner table are 1.5 mm and 0.5 mm, respectively. Focal lesions in skull may arise from bony structures, or they may be secondary to invasion of the skin - or brain-based lesions into bony structures. Benign lesions have well-defined borders and sclerotic margins whereas malignant lesions lead to destruction. Plain radiography is the first step in radiological evaluation followed by computed tomography (CT) and magnetic resonance imaging (MRI) if required. Imaging alone cannot differentiate various isolated atypical lytic lesions involving the skull. Clinical and radiological correlation is mandatory in reaching to a diagnosis. Histopathology remains the gold standard. We describe few atypical cases presenting as isolated lytic lesions of skull with characteristic imaging findings and a brief clinical approach to reach towards the diagnosis.

 Discussion



Isolated involvement of skull by a lymphoma usually occurs in immunocompromised patients. On imaging it is seen as a hyperdense mass on non-contrast images showing marked enhancement after contrast administration with bony destruction [Figure 1]. Histology shows lymphoid cells scattered in diffuse pattern. Immunohistochemistry is essential for further typing and characterization. Differentials include osteomyelitis and metastases. In osteomyelitis, fever and leukocytosis or other signs of inflammation are usually associated which help to clinch the diagnosis [Figure 2]. Histological examination in osteomyelitis reveals dead bone, inflammatory cells, granulation tissue and small vessel thrombosis. CT examination of chest and abdomen should be done in all the cases of lytic skull lesions to rule out a primary malignancy in the lungs and in the intra-abdominal organs [Figure 3]. [1] {Figure 1}{Figure 2}{Figure 3}

Hemangiopericytoma needs to be differentiated from meningiomas. On imaging, hemangiopericytoma appears as lobulated hyperdense mass with bone erosion without any evidence of calcification and hyperostosis [Figure 4]. Histological examination of hemangiopericytoma reveals uniformly cellular, variably ecstatic or compressed thin-walled branching vessels with gaping sinusoidal spaces (staghorn configuration). Tumor cells are spindled to round with small amounts of pale or eosinophilic cytoplasm, indistinct margins; bland vesicular nuclei. Meningiomas typically show a broad-based dural attachment on CT and MR studies whereas hemangiopericytoma has a narrow attachment with heterogeneous enhancement on post-contrast images. Histopathology of meningiomas depends on the grade. Depending on the grade, there may be presence of mitotic figures, sheeting, prominent nucleoli, hypercellularity, and the formation of small cells. Prominent internal flow voids may be seen on T2- weighted images in hemangiopericytoma. [2] {Figure 4}

Squamous cell carcinoma of scalp is seen in fifth to seventh decade of life and is a common cancer among Caucasians. Involvement of skull although rare, it is seen in organ transplant recipients with alopecia, HIV-infected patients, and patients with scleroderma or burn scars of the scalp. [3] Heterogenous soft tissue component predominantly towards the outer surface of calvaria and early involvement of superior sagittal sinuses are more commonly seen in appendageal squamous cell carcinoma of scalp [Figure 5]. [3],[4] Histology reveals prominent dyskeratosis, aberrant mitoses in epidermis along with parakeratosis.{Figure 5}

Langerhans cell histiocytosis is more common in the pediatric age group. Involvement of skull in Langerhans cell histiocytosis is seen classically as solitary or multiple punched out lytic lesions with or without sclerotic rim. Edges are bevelled due to greater involvement of the inner than the outer table and lytic lesion with button sequestrum representing residual bone or geographic skull may be seen [Figure 6]. [5] Histopathological examination reveals presence of histiocytes "LCH cells", macrophages, lymphocytes, eosinophils, giant cells and less commonly plasma cells and neutrophils. LCH cells may be abundant or scarce.{Figure 6}

 Teaching Point



Plain X-ray, CT and MRI are complementary tools for evaluating skull lesions. Patient age, history of trauma or a primary disease, enhancement pattern, presence of destruction or expansion, and the multiplicity of lesion should be taken into consideration. Biopsy and histopathological confirmation is the gold standard for definite diagnosis.

References

1Szucs-Farkas Z, Peltzer J, Berger D, Braunschweig M. Aggressive lymphoma of the skull in a patient with AIDS. JBR-BTR 2005;88:152-3.
2Chiechi MV, Smirniotopoulos JG, Mena H. Intracranial hemangiopericytomas: MR and CT features. AJNR Am J Neuroradiol 1996;17:1365-71.
3Neubauer KE, Goldstein GD, Plumb SJ. Squamous cell carcinoma of the scalp in organ transplant recipients: Exploring mechanisms for recurrence and treatment guidelines. Dermatol Surg 2010;36:185-93.
4Wollina U, Buslau M, Petrov I, Pramatarov K. Disabling pansclerotic morphea of childhood. Exp Rev Dermatol 2007;2:775-84.
5David R, Oria RA, Kumar R, Singleton EB, Lindell MM, Shirkhoda A, et al. Radiologic features of eosinophilic granuloma of bone. AJR Am J Roentgenol 1989;153:1021-6.