FINAL DIAGNOSIS Hodgkin's disease-mixed cellularity type.
This case was complex and surprising in that by pre-operative radiological studies the patient was felt to have a plexiform neurofibroma. Definitive diagnosis was not made at frozen section. The differential pathological diagnosis initially included follicular dendritic cell sarcoma, anaplastic Large Cell Lymphoma (ALK) or Hodgkin's Disease. Post operative scans showed extensive nodular residual mass extending into the soft tissues of the neck from the paraspinal region to deep to the sternocleidomastoid muscle. An incidental superior mediastinal mass lesion was noted adjacent to the trachea of mixed signal intensity with co-existent lymphadenopathy in both supraclavicular fossae. CT of thorax, abdomen and pelvis was carried out to further characterize the mediastinal lesion and look for other evidence of lymphadenopathy elsewhere. No other lesions were identified. A CT guided biopsy of the posterior mediastinal mass was carried out. This revealed features consistent with Hodgkin's lymphoma. Bone marrow biopsy was negative. Patient was considered to have stage IV Hodgkin's mixed-cellular type. The patient has been commenced on ABVD chemotherapy, she is currently undergoing her fourth cycle.
Primary CNS-Hodgkin's lymphoma (CNS-HL) is exceedingly rare with a reported incidence of 0.02-0.5% of all HL cases. (6,9). The literature available consists of case reports and small case series. Common presentations include cranial nerve palsies, motor/sensory deficits, headache, visual disturbance, seizures and coma.(8) Parenchymal disease is most common followed by dural based disease.(6) Paraspinal or spinal masses are not well described. Involvement of the dura mater may be de novo or may involve spread from a contiguous parenchymal lesion or metastases from systemic HL. (3,5,10). Median age at diagnosis is approximately 25 years.(6) There is a reported increased risk of CNS involvement in HL of a mixed-cellularity type (as in our patient) which accounts for up to 44% of CNS cases of HL.(1) In a recent case series of 16 patients with CNS-HL, 8 patients had CNS-HL occurring as a relapse of systemic disease, 2 had primary CNS-HL and 6 patients had evidence of systemic HL although it was initially discovered in the CNS. 5 cases had dural based non parenchymal tumors.(10) Although dural based HL mimicking meningioma has been described there are no previous reports of HL mimicking a plexiform neurofibroma in the literature.(4) In contrast there have been several cases of NHL mimicking both neurofibromatosis and meningiomas. (2,7) Because CNS involvement is rare in HL there is no consensus on therapy although various combinations of surgery, chemotherapy and radiation therapy were used in the recent series reported by Gerstner et al. Chemotherapy regimes varied widely. Our patient is currently receiving ABVD which was used in 2 patients in the Gerstner cohort with 50% success rate. (5) This case is unusual because CNS-HL involvement is extremely rare especially extracranially. When it does present in this fashion there may be evidence of systemic disease and the most common histological subtype is mixed cellularity-HL as in our patient. There are no previous reports of HL radiologically appearing identical to a paraspinal plexiform neurofibroma in the literature.
Contributed by Orna O’Toole, Alan O’Hare, Liam Grogan, Ciaran Bolger, Francesca M. Brett.