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Giant mediastinal parathyroid cyst masquerading as a substernal goiter
Giant mediastinal parathyroid cyst masquerading as a substernal goiter WILLIAM M. LYDIATT,MD,* ASHOK R. SHAHA, MD, IMTIAZ MUNSHI, MD, and RICHARD ROBBINS,MD, New York, New York
T h e differential diagnosis of an anterior mediastinal mass includes lesions involving the thyroid, parathyroid, thymus, lymphatic, nervous, or vascular structures. The most c o m m o n tumors include benign and malignant tumors of the thyroid, parathyroid, and thymus, as well as l y m p h o m a and sarcoma. Cystic lesions usually originate in the thymus, a substernal goiter, or are bronchogenic. We present a case o f a large parathyroid cyst causing tracheal deviation that masqueraded as a classic substernal thyroid.
At surgery a 6 × 6 x 4 cm, smooth, translucent cystic mass was identified. It was not adherent to the adjacent thyroid lobe and was retracted out of the mediastinum, preserving the recurrent laryngeal nerve. Pathologically the cyst wall was less than 1 mm thick and contained clear, watery fluid. The histopathologic analysis of the cyst wall revealed benign parathyroid tissue consistent with a parathyroid cyst (Fig. 2). The postoperative calcium level remained normal, and postoperative recovery was uneventful.
CASE REPORT
Large parathyroid cysts, although seen in 0.08% to 2.8% of autopsy specimens, are uncommon clinically, with less than 200 reported cases since Goris performed the first excision in 1905.1-4 De Quervain 5 reported the first substernal parathyroid cyst in 1925. Most parathyroid cysts arise from the inferior parathyroid glands and tend to present as neck masses, although approximately 15% occur in the mediastinum. 6,7 Most parathyroid cysts are asymptomatic, but mediastinal cysts may result in tracheal or esophageal compression, laryngeal nerve paresis, or pain. s,9 There is a female preponderance of almost 2 to 1. Approximately 10% to 15% of parathyroid cysts are functioning. No case of a malignant parathyroid cyst has been reported. The origin of parathyroid cysts is unknown, but Clark 8 reviewed several theories summarized as follows: (1) a retention of secretions, (2) a vestigial pharyngobronchial duct, (3) cystic degeneration of a parathyroid gland, (4) a coalescence o f Kfirsteiner canals (which are most abundant in the inferior parathyroid glands), and (5) infarction of a parathyroid adenoma. Clark believes that in cysts containing clear fluid, an embryologic origin is likely, given the occurrence of multiple cystic lesions in the same patient. Conversely, those with straw-colored or bloody fluid probably represent an infarcted adenoma. Diagnosis can be suspected on the basis of a cystic mass on ultrasonography with a fine-needle aspiration revealing clear, watery fluid. This fluid may show normal or elevated levels of total parathyroid hormone but usually will at least demonstrate an elevated C-terminal
A 70-year-old man sought medical attention when marked tracheal deviation was noted on a routine chest radiograph. He denied dysphagia, hoarseness, or stridor. He had no history of radiation exposure but had a strong family history of cancer in first-degree relatives. Physical examination demonstrated a 6 x 5 cm mass that was not fixed to the trachea and readily moved with swallowing. The lower border of the mass could not be palpated. Both vocal cords were mobile. The remainder of the head and neck examination was normal. Preoperative thyroid function and serum calcium levels were normal. CT of the neck and mediastinum revealed a 6 × 6 × 4.5 cm mass extending from the inferior lobe of the right thyroid into the superior mediastinum (Fig. 1). The initial impression was that of a substernal goiter with tracheal compression.
From the Department of Surgery, Head and Neck Service (Drs. Lydiatt, Shaha, and Munshi), and the Department of Medicine, Endocrinology Service (Dr. Robbins), Memorial Sloan-Kettering Cancer Center. Presented at the Annual Meeting of the American Academy of Otolaryngology-Head and Neck Surgery, New Orleans, La., Sept. 17-20, 1995. *Dr. Lydiatt is currently affiliated with the University of Nebraska Medical Center and Methodist Hospital, Omaha, Neb. Reprint requests: Ashok R. Shaha, MD, Department of Surgery, Head and Neck Service, Memorial Sloan-Kettering Cancer Center, 1275 York Ave., New York, NY 10021. Otolaryngol Head Neck Surg 1997;116:411-3. Copyright © 1997 by the American Academy of OtolaryngologyHead and Neck Surgery Foundation, Inc. 0194-5998/97/$5.00 + 0 23/4/74529
DISCUSSION
411
412 LYDIAI"r et al.
OtolaryngologyHead and Neck Surgery March 1997
Fig. 1. Axial CT scan demonstrating large cystic mass with deviation of the trachea and extension into superior mediastinum.
Fig. 2. High-power micrograph demonstrating thin cystic wail with normal parathyroid tissue. (Original magnification × 40.)
OtolaryngologyHead and Neck Surgery Volume 116 Number 3
parathormone level. 3,1° The calcium level may also be normal or elevated. Aspiration of the cyst may be curative in some cases and is worthwhile when the cyst is accessible.S, ll If repeat aspiration fails, curative surgical excision can be performed safely with minimal morbidity. In the absence of preoperative hyperparathyroidism, postoperative hypocalcemia is rare. At presentation our patient had an incidental superior mediastinal mass that clinically and radiographically suggested a substernal goiter. The intraoperative finding of a large parathyroid cyst was a surprise, and we therefore had not attempted aspiration. The mass required meticulous dissection in the superior mediastinum with preservation of the recurrent laryngeal nerve. Pathologic analysis revealed the presence of normal parathyroid tissue in the wall, which confirmed the diagnosis of parathyroid cyst.
LYDIATTet al. 4 1 3
REFERENCES 1. WeltiH. Apropos des kystes parathyroidiens.Mere Acad Chit 1946;72:33-5. 2. Gilmour JR. The normal histology of the parathyroid glands, a Pathol BacterioI 1939;48:187-222. 3. BurhopJW, CerlettyJM, DemeureMJ. Elevatedcalciumlevelin parathyroid cyst fluid. EndocrinePractice 1995;1:32-4. 4. Goris D. Extirpation de trois Iobules parathyroikenskystiques. Ann Soc Belge Chir 1905;5:394-8. 5. De Quervain F. Chirurgishe demonstrationen. (EpithelKorperchen-Cysti).Schweiz Med Wochenschr 1925;55:1168. 6. Margolis1B, WayneR, OrganCH. Parathyroid cysts: functional and mediastinal.Surgery t975;77:462-6. 7. Guvendik L, Oo LK, Roy S, Donaldson LA, Kennedy DD. Managementof a mediastinalcyst causinghyperparathyroidism and tracheal obstruction.Ann Thorac Surg 1993;55:167-8. 8. Clark OH. Parathyroidcysts. Am J Surg 1978;135:395-402. 9. ThackerWC, WellsVH, Hall ER. Parathyroidcyst of the mediastinum.Ann Surg 1971;174:969-75. 10. SilvermanJF, Khizanie PG, Norris KT, Fore WW. Parathyroid hormone (PTH) assay of parathyroid cysts examined by fineneedle aspirationbiopsy. Am J Clin Pathol 1986;86:776-80. 11. Katz AD, Dunkleman D. Needle aspiration of nonfunctioning parathyroid cysts. Arch Surg 1984;119:307-8.
BOUND VOLUMES AVAILABLE TO SUBSCRIBERS Bound volumes of Otolaryngology-Head and Neck Surgery are available to subscribers (only) for the 1997 issues from the Publisher, at an individual cost of $89.50 ($115.03 for Canadian, $107.50 for international subscribers) for Vols. 116 (January-June) and 117 (JulyDecember). Shipping charges are included. Each bound volume contains subject and author indexes, and all advertising is removed. Copies are shipped within 60 days after publication of the last issue in the volume. The binding is durable blue buckram with the Journal name, volume number, and year stamped in gold on the spine. Payment must accompany all orders. Contact Mosby-Year Book, Inc., Subscription Services, 11830 Wesfline Industrial Drive, St. Louis, MO 63146-3318, USA; phone (800)453-4351 or (314)453-4351. Subscriptions must be in force to qualify. Bound volumes are not available in place of a regular Journal subscription.
T h e differential diagnosis of an anterior mediastinal mass includes lesions involving the thyroid, parathyroid, thymus, lymphatic, nervous, or vascular structures. The most c o m m o n tumors include benign and malignant tumors of the thyroid, parathyroid, and thymus, as well as l y m p h o m a and sarcoma. Cystic lesions usually originate in the thymus, a substernal goiter, or are bronchogenic. We present a case o f a large parathyroid cyst causing tracheal deviation that masqueraded as a classic substernal thyroid.
At surgery a 6 × 6 x 4 cm, smooth, translucent cystic mass was identified. It was not adherent to the adjacent thyroid lobe and was retracted out of the mediastinum, preserving the recurrent laryngeal nerve. Pathologically the cyst wall was less than 1 mm thick and contained clear, watery fluid. The histopathologic analysis of the cyst wall revealed benign parathyroid tissue consistent with a parathyroid cyst (Fig. 2). The postoperative calcium level remained normal, and postoperative recovery was uneventful.
CASE REPORT
Large parathyroid cysts, although seen in 0.08% to 2.8% of autopsy specimens, are uncommon clinically, with less than 200 reported cases since Goris performed the first excision in 1905.1-4 De Quervain 5 reported the first substernal parathyroid cyst in 1925. Most parathyroid cysts arise from the inferior parathyroid glands and tend to present as neck masses, although approximately 15% occur in the mediastinum. 6,7 Most parathyroid cysts are asymptomatic, but mediastinal cysts may result in tracheal or esophageal compression, laryngeal nerve paresis, or pain. s,9 There is a female preponderance of almost 2 to 1. Approximately 10% to 15% of parathyroid cysts are functioning. No case of a malignant parathyroid cyst has been reported. The origin of parathyroid cysts is unknown, but Clark 8 reviewed several theories summarized as follows: (1) a retention of secretions, (2) a vestigial pharyngobronchial duct, (3) cystic degeneration of a parathyroid gland, (4) a coalescence o f Kfirsteiner canals (which are most abundant in the inferior parathyroid glands), and (5) infarction of a parathyroid adenoma. Clark believes that in cysts containing clear fluid, an embryologic origin is likely, given the occurrence of multiple cystic lesions in the same patient. Conversely, those with straw-colored or bloody fluid probably represent an infarcted adenoma. Diagnosis can be suspected on the basis of a cystic mass on ultrasonography with a fine-needle aspiration revealing clear, watery fluid. This fluid may show normal or elevated levels of total parathyroid hormone but usually will at least demonstrate an elevated C-terminal
A 70-year-old man sought medical attention when marked tracheal deviation was noted on a routine chest radiograph. He denied dysphagia, hoarseness, or stridor. He had no history of radiation exposure but had a strong family history of cancer in first-degree relatives. Physical examination demonstrated a 6 x 5 cm mass that was not fixed to the trachea and readily moved with swallowing. The lower border of the mass could not be palpated. Both vocal cords were mobile. The remainder of the head and neck examination was normal. Preoperative thyroid function and serum calcium levels were normal. CT of the neck and mediastinum revealed a 6 × 6 × 4.5 cm mass extending from the inferior lobe of the right thyroid into the superior mediastinum (Fig. 1). The initial impression was that of a substernal goiter with tracheal compression.
From the Department of Surgery, Head and Neck Service (Drs. Lydiatt, Shaha, and Munshi), and the Department of Medicine, Endocrinology Service (Dr. Robbins), Memorial Sloan-Kettering Cancer Center. Presented at the Annual Meeting of the American Academy of Otolaryngology-Head and Neck Surgery, New Orleans, La., Sept. 17-20, 1995. *Dr. Lydiatt is currently affiliated with the University of Nebraska Medical Center and Methodist Hospital, Omaha, Neb. Reprint requests: Ashok R. Shaha, MD, Department of Surgery, Head and Neck Service, Memorial Sloan-Kettering Cancer Center, 1275 York Ave., New York, NY 10021. Otolaryngol Head Neck Surg 1997;116:411-3. Copyright © 1997 by the American Academy of OtolaryngologyHead and Neck Surgery Foundation, Inc. 0194-5998/97/$5.00 + 0 23/4/74529
DISCUSSION
411
412 LYDIAI"r et al.
OtolaryngologyHead and Neck Surgery March 1997
Fig. 1. Axial CT scan demonstrating large cystic mass with deviation of the trachea and extension into superior mediastinum.
Fig. 2. High-power micrograph demonstrating thin cystic wail with normal parathyroid tissue. (Original magnification × 40.)
OtolaryngologyHead and Neck Surgery Volume 116 Number 3
parathormone level. 3,1° The calcium level may also be normal or elevated. Aspiration of the cyst may be curative in some cases and is worthwhile when the cyst is accessible.S, ll If repeat aspiration fails, curative surgical excision can be performed safely with minimal morbidity. In the absence of preoperative hyperparathyroidism, postoperative hypocalcemia is rare. At presentation our patient had an incidental superior mediastinal mass that clinically and radiographically suggested a substernal goiter. The intraoperative finding of a large parathyroid cyst was a surprise, and we therefore had not attempted aspiration. The mass required meticulous dissection in the superior mediastinum with preservation of the recurrent laryngeal nerve. Pathologic analysis revealed the presence of normal parathyroid tissue in the wall, which confirmed the diagnosis of parathyroid cyst.
LYDIATTet al. 4 1 3
REFERENCES 1. WeltiH. Apropos des kystes parathyroidiens.Mere Acad Chit 1946;72:33-5. 2. Gilmour JR. The normal histology of the parathyroid glands, a Pathol BacterioI 1939;48:187-222. 3. BurhopJW, CerlettyJM, DemeureMJ. Elevatedcalciumlevelin parathyroid cyst fluid. EndocrinePractice 1995;1:32-4. 4. Goris D. Extirpation de trois Iobules parathyroikenskystiques. Ann Soc Belge Chir 1905;5:394-8. 5. De Quervain F. Chirurgishe demonstrationen. (EpithelKorperchen-Cysti).Schweiz Med Wochenschr 1925;55:1168. 6. Margolis1B, WayneR, OrganCH. Parathyroid cysts: functional and mediastinal.Surgery t975;77:462-6. 7. Guvendik L, Oo LK, Roy S, Donaldson LA, Kennedy DD. Managementof a mediastinalcyst causinghyperparathyroidism and tracheal obstruction.Ann Thorac Surg 1993;55:167-8. 8. Clark OH. Parathyroidcysts. Am J Surg 1978;135:395-402. 9. ThackerWC, WellsVH, Hall ER. Parathyroidcyst of the mediastinum.Ann Surg 1971;174:969-75. 10. SilvermanJF, Khizanie PG, Norris KT, Fore WW. Parathyroid hormone (PTH) assay of parathyroid cysts examined by fineneedle aspirationbiopsy. Am J Clin Pathol 1986;86:776-80. 11. Katz AD, Dunkleman D. Needle aspiration of nonfunctioning parathyroid cysts. Arch Surg 1984;119:307-8.
BOUND VOLUMES AVAILABLE TO SUBSCRIBERS Bound volumes of Otolaryngology-Head and Neck Surgery are available to subscribers (only) for the 1997 issues from the Publisher, at an individual cost of $89.50 ($115.03 for Canadian, $107.50 for international subscribers) for Vols. 116 (January-June) and 117 (JulyDecember). Shipping charges are included. Each bound volume contains subject and author indexes, and all advertising is removed. Copies are shipped within 60 days after publication of the last issue in the volume. The binding is durable blue buckram with the Journal name, volume number, and year stamped in gold on the spine. Payment must accompany all orders. Contact Mosby-Year Book, Inc., Subscription Services, 11830 Wesfline Industrial Drive, St. Louis, MO 63146-3318, USA; phone (800)453-4351 or (314)453-4351. Subscriptions must be in force to qualify. Bound volumes are not available in place of a regular Journal subscription.