Mucous membrane pemphigoid, thymoma, and myasthenia gravis

In November 1997, approximately 1 year before being evaluated at the Mayo C linic, Rochester, a 63 year-old woman presented with erosive tongue lesions that were diagnosed by her physician as oral lichen planus. The lesions re sponded well to 3 months of treatment with systemic and topical corticoster oids and topical antiyeast medication. She stopped taking the medications a nd had a relapse. A few months after the oral lesions developed, her left e yelid became ptotic. Results of magnetic resonance imaging of her brain wer e normal, and the ptosis resolved spontaneously after 2 weeks. One year lat er, her right eyelid began to droop, and the results of edrophonium testing were positive. She was prescribed prednisone, 30 mg daily, and pyridostigm ine, as needed. The ptosis improved, but never fully resolved. Radiography revealed a left "thyroid nodule," but computed tomography did not show a me diastinal mass. She was advised to have the "nodule" removed surgically and came to the Mayo Clinic, Rochester, for a second opinion. Her medical history was significant for the following: tinnitus, glaucoma, early bilateral cataracts, and long-standing hypertension, for which she to ok losartan, 50 mg twice daily. Other medications included: prednisone, 30 mg daily; pyridostigmine as needed; famotidine, 40 mg daily; and eyedrops f or glaucoma. She denied any history of hyperthyroidism or hypothyroidism, h ead and neck irradiation, family history of thyroid disease, or diplopia. H epatitis serologic studies revealed hepatitis B exposure and recovery, hepa titis C immunity, and a previous hepatitis A viral infection. On examination at the Mayo Clinic, Rochester, an erosive hypertrophic plaqu e was noted on the posterior dorsal half of the tongue, and vesicles and er ythematous erosions on the hard and soft palates (Fig. 1a). A lace-like whi te pattern was seen on the buccal mucosa bilaterally, and a small erosive p atch on the left buccal mucosa (Fig. 1b). Ocular and nasal mucous membranes were normal in appearance, and there were no pertinent skin findings. Derm atopathologic examination of an excisional biopsy specimen from the left do rsum of the tongue demonstrated an ulcer with epitheliomatous hyperplasia a nd a granulomatous reaction, presumably due to yeast infection. Silver stai ning showed hyphae and yeast at the base of the tongue ulcer. The results o f the direct immunofluorescence study were negative and revealed no licheno id changes on hematoxylin and eosin staining. Indirect immunofluorescence t esting of the serum revealed a 1 : 80 titer of basement membrane zone antib odies, reflecting pemphigoid. This test was positive on repeat study. Salt- split skin on monkey esophagus revealed an epidermal pattern of basement me mbrane zone antibodies. Treatment included fluocinonide gel applied to the involved areas four times daily and oral antiyeast therapy (fluconazole, 20 0 mg once daily by mouth) while the rest of the evaluation was being comple ted. As part of the evaluation of the ptosis, a myasthenia gravis antibody panel was performed. It revealed the following abnormalities: striated muscle an tibody at 1 : 480 (reference range, <1 : 60), acetylcholine receptor bindin g antibody at 6.33 nmol/L (reference range, less than or equal to 0.02 nmol /L), acetylcholine receptor blocking antibody at 31% (reference range, 0-25 %), and acetylcholine receptor modulating antibody at 100% (reference range , 0-20%), suggesting thymoma. Treatment included pyridostigmide, 30-45 mg 3 -4 times daily, to control the myasthenia symptoms, while the ill-defined n eck mass was being evaluated. A mildly enlarged thyroid was noted on physical examination. Hematology pan el revealed thyroid-stimulating hormone (TSH) levels in the low normal rang e; the thyroid microsomal antibody was normal. Chest radiography showed min or tracheal deviation, and a previous computed tomogram showed what appeare d to be a 3-cm enlarged mass in the thyroid. Ultrasonographically guided th yroid biopsy did not show malignancy, but a benign mesenchymal-type tumor w as found and surgical excision was planned. Intraoperatively, a thymoma of the left cervical thymic tongue was found. At 6 months' follow-up, the ptosis and oral mucosal lesions had improved si gnificantly, although she continued topical corticosteroid therapy intermit tently for minor erosive oral disease.