Neurological paraneoplastic syndromes

Myasthenia gravis associated with malignant mixed Mullerian tumor of the uterus

Myasthenia gravis is a neurologic disorder characterized by intermittent muscle weakness which improves after anticholinesterase medication. The pathogenesis of myasthenia gravis is associated with production of autoantibodies to nicotinic acetylcholine receptor in the motor end plate. Most patients do not have an underlying neoplasm, but in 10-15% of the cases, a thymoma may be detected. Apart from thymoma, no other tumor type or organ has consistently been associated with myasthenia gravis. We describe an unusual case of myasthenia gravis in a patient with malignant mixed Mullerian tumor of the uterine corpus. Initial histology revealed malignant mixed Mullerian tumor of a predominant carcinomatous element. At that time, there were no symptoms of muscle weakness. Intraabdominal metastases were detected later, concommitantly with symptoms of muscle weakness and the diagnosis of myasthenia gravis. Histology of the metastases disclosed an exclusive mesenchymal element with striated muscle differentiation. To the best of our knowledge this case is the first report of myasthenia gravis in a patient with malignant mixed Mullerian tumor of the uterine corpus. We propose that the mechanism contributing to myasthenia gravis in this patient was closely associated with the evolving histology and with the nature of the tumor, so that antibodies produced to muscle-like epitopes exposed by malignant cells could have cross-reacted with acetylcholine nicotinic receptors and caused myasthenia gravis.

Hypertension as a paraneoplastic phenomenon in childhood Hodgkin's disease

A 14 year old girl with Hodgkin's disease presented with hypertension as an unusual paraneoplastic phenomenon. The elevated plasma renin activity recorded in this patient was possibly a result of Hodgkin's disease. Hypertension as well as plasma renin activity declined to normal values following her successful response to chemotherapy.

Circulating antineuronal antibodies reach neurons in vivo: an autopsy study

In serum and cerebrospinal fluid of 6 out of 15 patients with small cell lung cancer circulating antineuronal antibodies could be detected by indirect immunofluorescence. None of the patients showed signs of a neurological paraneoplastic syndrome, usually associated with the presence of these antibodies. On sections of frontal brain, cerebellum, dorsal root ganglia and peripheral nerve, obtained at autopsy, a direct immunofluorescence test was performed. Only in antibody-positive individuals were membrane-bound immunoglobulin deposits detected on neurons of dorsal root ganglia and Purkinje cells. The present study showed that circulating antineuronal antibodies reach the central and peripheral nervous system in vivo. These findings support the theory that these antibodies might be directly involved in the pathogenesis of neurological paraneoplastic syndromes.

Anti-neuronal antibodies in paraneoplastic neurological disorders with small-cell lung carcinoma

Auto-antibodies of the neuronal anti-nuclear antibody (anti-Hu) type were found in serum of three patients suspected of a paraneoplastic syndrome of the central nervous system. In all three a small cell carcinoma of the lung was detected. The sera showed bright staining of neuronal nuclei sparing the nucleolus. In two patients the antibody was of the IgG class (titers 1:1600 and 1:4000). In one patient only an IgM class antibody was present (titer 1:1000). The presence of the anti-Hu antibody strongly supports a diagnosis of a paraneoplastic neurological syndrome associated with small cell carcinoma of the lung.