Non-Hodgkin’s lymphoma of the cranial cavity may be present due to metastatic deposit of systemic lymphoma in 1–6% cases and cranial vault in less than 1% cases, but primary NHL of the cranial vault is rare. [1, 2] Not more than 50 cases have been reported to date. Primary cranial vault lymphoma had been defined as localized lymphoma not involving other than the primary site for more than 6 months, once we made the initial diagnosis [3]. In primary calvaria lymphoma, the most common histopathology reported is NHL large B-cell type (39–78%), and in primary Dural lymphoma most common pathology reported is marginal B cell lymphoma which is low grade.
In the El Asri et al. meta-analysis, the average age at presentation was 60 years without any gender prevalence. The average duration was the onset of symptoms was average of 1 year [4]. In the present case report, the patient noticed swelling 5 years back on the right parieto-occipital region, which was of the size of grapes, but he was inflicted with COVID twice within 1 year at an interval of 6 months, and there was a fast progression of size and patient noticed another three lesions on the scalp. We may attribute this fast progression to the immunosuppression caused by COVID 19 treatment and the immunosuppressive therapy he had received during his treatment, as he developed a drastic fall in oxygen saturation of 80% in both episodes of COVID 19 infection. In studies of El Asri et al. and Ferreri et al., the immunosuppressed condition was reported in nearly 11% of patients [4, 5].
In the present study, tumor characteristics on T1 and T2 weighted MRI were almost similar to the other reported patients with similar histopathology, and it homogenously contrasts enhanced with Dural tail sign. We noticed selective permeation of tumor mass through the cranial vault with tumor deposit on the inner table of calvaria and seeding of the dura in the anterior frontal region, causing mass effect and no visualization of the anterior sagittal sinus. On DSA tumor was being fed from bilateral ECA with tumor blush present suggesting vascular lesion, and left transverse sinus was also not visualized. Angiographic findings favor meningioma as lymphomas are not reported to have vascular blush on angiography except in 2–3 reported patients in the literature [3, 6].
Our patient’s MRI findings did not reveal any widening of diploic space, and there were slightly cortical changes and patchy contrast enhancement suggestive of permeation of calvaria cortex by malignant lymphomatous cells. Anterior sagittal sinus was not visualized, probably due to overlying compression by tumor mass and metastatic deposit through emissary’s veins. As the lesion was high-grade permeation of left transverse sinus through emissary veinous channel leading to thrombosis may be the reason. Such selective permeation of malignant lymphomatous cells was reported in the study by Ochiai et al. and Galarza et al. [7, 8]. In the study by Kissling et al., the lymphomatous mass resembling meningioma has diffuse osteolytic features with thrombosis of the posterior third sagittal sinus [3].
Such atypical radiological findings probably have not been reported.
Faster progression of the tumor was reflected by high KI-67 proliferation index, but one good prognostic feature was the absence of BCL-2 staining, which helps in good chemotherapy and radiotherapy response as reported in different studies [9]. In the previous, reported cases mimicking meningioma BCL-2 staining in FISH were presented, suggesting a poor response to treatment [3, 8]. We did not find an extended follow-up in these reports. In the study by Ciarpaglini et al., high-grade lesions survive from 10 to 17 months, and in low-grade 5 years, survival is around 40–50% [10]. Although our patient developed a multicentric tumor over time, less tumor bulk and good histopathology for chemo and radiotherapy had given the advantage of better survival. He is asymptomatic after treatment on 5 months of follow-up and no fresh lesion on repeat MRI.
We thought to report this case due to unusual association with COVID 19 and atypical presentation, which was not reported in the earlier reported case, presenting a diagnostic and management dilemma to us. Patients having cranial vault primary DLBCL with the benign course may convert into aggressive lesions following infliction with the immunosuppressed state as in the present patient study and may present as a diagnostic dilemma. However, early excisional diagnosis and favorable immunostaining with BCL-2 may add survival benefits.