Table 1.

French Cohort of Patients With MCC-Related PNS

Nº/Age	Clinical picture	First diagnosis–delaya	Tumor status at PNS diagnosis	Antibody	PNS-Care Score	MRI	CSF	ImmunoT	OncoT	Comments
1/7th decade	LEMS	PNS–2 mo	Lymph node, primary unknown	CSF VGCC + atypical anti-NFb	9	Normal	11 WBCs	Steroids, IVIG, RTX, CPP	Surgery, RT, CT	Tumor MCPyV+ RPCS associated
2/6th decade	LEMS	Tumor–6 mo	Lymph node	Negative	7	Normal	OCB	Steroids, IVIG, PLEX, RTX, MM	Surgery, RT	RPCS associated
3/6th decade	LEMS	PNS–2 mo	Lymph node	CSF unknown neuropil Ab	7	Leptomeningeal enhancement	Prot 74 mg/dL	Steroids, IVIG, CPP	Surgery	Tumor MCPyV+ RPCS associated
4/9th decade	RPCS	PNS–1 mo	NA	CSF atypical anti-NFb	7	Normal	Prot 80 mg/dL	No	No
5/5th decade	RPCS	PNS–1 mo	Lymph node, primary unknown	CSF VGCC Anti-NF medium chain	9	T2 HS in the cervical spinal cord, cerebellum, and conus medullaris	9 WBCs, Prot 80 mg/dL	Steroids, IVIG, CPP	Surgery, RT	Associated myelitis
6/6th decade	RPCS	PNS–2 mo	Local tumor	CSF unknown antineuronal Ab	7	Normal	NA	No	Surgery, RT, CT
7/8th decade	RPCS	PNS–1 mo	Lymph node, primary unknown	CSF anti-NF heavy, medium, and light chains	7	Normal	7 WBCs, Prot 66 mg/dL	IVIG	No
8/8th decade	EM	PNS–7 mo	Lymph node	Serum GAD >1/4,000	7	Normal	55 WBCs	No	Surgery, RT
9/8th decade	EM	PNS–8 mo	Lymph node, primary unknown	Serum CV2/CRMP5	10	T2 HS in bilateral caudate and lenticular nucleus	Prot 245 mg/dL	Steroids, IVIG, CPP	CT, RT
10/8th decade	EM	Tumor–12 mo	Lymph node	Serum Hu	10	T2 white matter HS	Normal	Steroids	Surgery, RT
11/8th decade	EM	PNS–6 mo	Lymph node, primary unknown	CV2/CRMP5	10	Basal ganglia HS	250 mg/dL	Steroids, IGIV, CPP	Qx, RT, QT
12/7th decade	Brainstem encephalitis	PNS–1 mo	Lymph node, primary unknown	CSF anti-NF medium chain	6	T2 HS in bilateral superior cerebellar peduncles	Normal	Steroids, IVIG, PLEX	Surgery, RT
13/8th decade	Brainstem encephalitis	PNS–1 mo	Lymph node, primary unknown	CSF anti-NF medium, light, and alfa-internexin chains	6	Normal	NA	IGIV	No
14/6th decade	Extralimbic encephalitis	Tumor–13 mo	Local tumor	CSF anti-NF heavy, medium, light, and alfa-internexin chains	6	Diffuse WM HS	380 WBCs, 250 mg/dL	Steroids, IGIV	Qx	Bilateral optic neuritis and Sjogren syndrome
15/8th decade	Myelitis	PNS–1 mo	Lymph node, primary unknown	CSF anti-NF heavy, medium, light, and alfa-internexin chains	6	C2-C5 + T2 HS	50 WBCs, 190 mg/dL	Steroids, PLEX	Qx, RT
16/9th decade	Autonomic neuronopathy	Tumor–2 mo	Lymph node	Serum Hu	10	NA	Prot 66 mg/dL	No	Surgery, RT
17/7th decade	Motor neuron disease	PNS–3 mo	Lymph node	Serum VGCC	3	Normal	NA	Steroids, cyclosporine (kidney graft)	Surgery, RT

Abbreviations: Ab = antibody; CT = chemotherapy; EM = encephalomyelitis; GAD = glutamate decarboxylase; HS = hyperintensity; ICI = immune checkpoint inhibitor; ImmunoT = immunotherapy; IVIG = IV immunoglobulin; LEMS = Lambert-Eaton myasthenic syndrome; NA = not available; OCB = oligoclonal band; OncoT = oncotherapy; MCPyV = Merkel cell polyomavirus; ML = molecular layer; NF = neurofilament = ON = optic neuritis; PLEX = plasma exchange; PNS = paraneoplastic neurologic syndrome; RPCS = rapidly progressive cerebellar syndrome; RT = radiotherapy; VGCC = voltage-gated calcium channel; WBCs = white blood cells; WM = white matter.

^aDelay was defined as the time between the diagnosis of the PNS and that of the tumor or from the diagnosis of the tumor and that of the PNS.

^bThese patients had a neurofilament-like staining on tissue-based immunofluorescence but were negative on cell-based assays transiently transfected to express heavy-chain NF, medium-chain NF, light-chain NF, or α-internexin.