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Case Reports Indian Pediatrics 2000;37: 1010-1013 |
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Mesenchymal Hamartoma of Chest Wall in a Newborn |
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Mesenchymal hamartoma of the chest wall (MHCW) is a very rare, benign tumor with unique location (arising from the ribs), distinct clinical, radiological and histopathologic characteristics. We herewith report a case and review the literature of this rare entity that can be easily mistaken for a malignant tumor.
A full term female neonate with birth weight of 2990 grams, and gestational age of 39 weeks was found to have a large lump on the anterior aspect of the right side of the chest wall at birth. The baby was born to a 34-year old G4P1 mother, pregnancy was uncomplicated, and the mal-formation scan performed during preganancy at 18 weeks of gestation did not reveal any abnormality. The APGAR scores were 9 and 9 at 1 and 5 minutes, respectively; and no resus-citation was required at birth. The patient was admitted to neonatal intensive care for evalua-tion of the chest mass. There was no respiratory distress. Physical examination revealed a well newborn with normal vital signs, and pink color in room air. There was a 2.5 ´ 3.0 cm nontender hard lump in the region of the middle part of the right side of the chest. The remainder of the general physical examination was normal. A chest X-ray examination showed a rim of calcified mass arising from the posterior part of the right 3rd rib, and a lobulated mass extending inferior to it (Fig. 1). A CT scan revealed an expansile mass, 4 cm in diameter, arising from the right posterior third rib (Fig. 2). The mass contained a central mixed density with some fluid. There was thick irregular bone matrix surrounding this mass as well as center within it. There was cardio-mediastinal rotation to the left. A second mass was seen anteriorly, arising from the anterior end of the first rib in the region of costocartilage. This was of predominantly soft tissue density with some central calcification. There was no abnormality in the lung paren-chyma and no lymphadenopathy. Results of abdominal ultrasound examination and skeletal survey were normal. A provisional diagnosis of mesenchymal hamartoma of the chest wall was made. At 7 days of age the patient had complete resection of the anterior chest mass, to establish histologic diagnosis. The posterior mass was not resected. The postoperative course was unevent-ful. Gross examination of specimen showed a smooth hemorrhagic semicystic mass arising from the costocartilage. Histopathologic examination showed a benign hamartoma with cellular fibroblastic tissue, islands of cartilage and bone with some cystic areas, and fat tissue consistent with the diagnosis of mesenchymal hamartoma. After establishing the diagnosis of mesen-chymal hamartoma of chest wall the inital management plan was to follow the patient periodically with the expectation that the posterior mass would regress and disappear spontaneously over a period of time. However, a follow-up CT scan at 3˝ months of age revealed increase in the size of the posterior chest mass with significant compression of lung parenchyma. Complete resection of posterior mass was carried out at 4 months of age.
MHCW is a rare tumor that may arise antenatally and typically present at birth or in early infancy as a chest wall mass with or without respiratory distress, and with marked rib deformity(1-10). The tumor arises from the ribs and consists of partially mineralized focal overgrowths of normal skeletal elements with no malignant tendency(1-10). To the best of our knowledge there are 57 cases (including our case) of MHCW reported in the literature with male: female ratio of 2:1, and the age at the time of presentation ranging from birth to 16 years. About half of these patients had respiratory symptoms or signs at presentation(1-10). Several imaging techniques have been used for diagnosis of MHCW. The diagnosis of MHCW may be revealed on the chest radiograph and appears as a large partially calcified well-defined extrapleural mass arising from one or more than one ribs. The involved ribs may be expanded, distorted and partially destroyed. CT scan is the optimal method of imaging and helps to determine the site of origin, tumor density, enlargement and effect on adjacent structures(1,2,7,9). MRI has also been used as an alternative imaging modality(9). Detection of the tumor by antenatal ultrasound has been reported in few cases(4,8). The definitive diagnosis of MHCW is established only by histopathological examina-tion(1,3), MHCW are well circumscribed, and the cut surface shows both cystic and solid components, and composed of two or more cell types of mesenchymal origin not ordinarily found together. Microsopically, this tumor is composed predominantly of chondroid tissue with large endothelium lined blood spaces and primitive mesenchyme with osteoclastic giant cells, endochondral ossification and maturation to trabecular bone. The tumor should be differentiated from chondroblastoma, osteo-blastoma, aneurysmal bone cyst, and other mesenchymal neoplasms(1-10). Radiologically this lesion can sometimes be confused with malignant tumor: congenital neuroblastoma, Ewing's sarcoma and malignant teratoma(1). None of the tumors discussed here in the differential diagnosis of MHCW have been diagnosed at birth, and they are extremely rarely localized in the rib(1). Management of this condition may be conservative or surgical depending on the clinical presentation of the patient(1,2,7). Of the 57 cases described in literature; 48 cases were managed by complete resection, 2 cases by partial resection with no further recurrence, 5 cases by diagnostic biopsy followed by conservative expectant management leading to complete regression, and 2 babies died on day 1 of life. Spontaneous regression of the bilateral chest wall mesenchymal hamartoma has been documented(1,2,6). The tumor usually stops growing within the first year of life and in some instances surgery may not be necessary(2,7,9). Sympotomatic patients having cardiorespiratory compromise or patients in whom the lesion itself is causing deformity are best treated surgically, by complete resection(1,2,4,7). Treatment of the asymptomatic cases is controversial; both complete resection and conservative manage-ment are advocated (1,2,6). Scoliosis may occur after surgical resection and is reported in 6 cases(1,2,6). Open biopsy and partial resection may become complicated by hemorrhage because of prominent vascularity of MHCW(1). It is necessary to recognize this rare entity before surgery to avoid over-treatment(1,6). In our case after establishing the diagnosis the posterior mass was intially treated conser-vatively with regular follow up in the hope that the mass would regress completely and spontaneously. However, a follow up CT scan of chest at 3˝ months of age revealed an increase in the size of the posterior chest mass with significant compression of lung parenchyma, prompting complete resection. Contributors: All were involved in case management and contributed to manuscript preparation. Funding:
None.
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