sum of two units asymptomatic paravertebral thoracic masses occurr in a 65-year-old patient with isolated macrocytosis.

sum of two units asymptomatic paravertebral thoracic masses occurr in a 65-year-old patient with isolated macrocytosis. The largest single measured 8 cm and was surgically resect with a presumptive diagnosis of schwannoma. This thoracic mass was hemorrhagic, encapsulated, and compos of fat and hematopoietic tissue. While extramedullary hematopoietic tumors usually present itself in patients with severe chronic hemolytic anemia, our report proposes that such lesions must be considered in the differential diagnosis of posterior mediastinal mass in patients without clinically evident anemia.

(Chest 1993; 104:1623-24)

EMHT = extramedullary hematopoietic tumor

Extramedullary hematopoietic tumors (EMHTs) that bear likeness [i]or[/i] resemblance to myelolipomas may occur when the normal function of bone marrow is disturbed.[1] In the posterior mediastinum, EMHT are usually associated with chronic congenital hemolytic anemia.[1-6] These tumors near as asymptomatic, unilateral, or bilateral paraspinal masses.

A single case of mediastinal EMHT associated with macrocytosis related to vitamin deficiency has been reported.7 This report nears the first case (to our knowledge) associated with primary refractory anemia that was confirmed by dint of histologic examination of the surgically remov mass.

Case Report

A 65-year-old man was referr to the Marie Lannelongue Hospital for a right femoral bypass. He had a history of partial gastrectomy at the age of 25 years and had smok common pack of cigarettes a day for 45 years.

A right paravertebral thoracic mass was incidentally discovered upon preoperative chest radiographs. The lesion was already at hand on systematic radiographs performed 2 years before. The patient was not investigated further at that time. He had no thoracic symptom, no excitement and no weight loss.

Laboratory findings included the following: a WBC regard of 8 x [10.sup.9]/L with neutrophils 65 percent lymphocyte 29 percent and monocytes 6 percent; an erythrocyte look upon of 3.35 x [10.sup.12]/L with hemoglobin concentration of 127g/L hematocrit of 37 percent and mean corpuscular mass of 110 fl; and a platelet deem of 250 x [10.sup.9]/L. Other pertinent laboratory serum values were as follows: normal creatinine and liver chemistry studies, total bilirubin of 22 [mu]movl/L (N<20) released bilirubin of 20 [mu]mol/L, vitamin [Bsub12] of 353 ng/L (N>130) and folate of 28 [mu]g/L (N>18)

Fiberoptic bronchoscopy revealed no lesion and aortography showed no argument for pulmonary sequestration. Comput tomography showed couple paravertebral masses at the T9 horizontal (Fig 1). The right mass and the left measured 8 and 35 cm respectively These tumors had a plain margination and were composed of areas of gentle density suggestive of fat deposition and of regions of water density. There was no calcification. The bone were normal and not eroded

With a presumptive diagnosis of schwannoma, the patient underwent right thoracotomy The subpleural mass had no connection with ribs or vertebrae. This tumor was easily dissected from the chest wall and was remov without break The diagnosis of extramedullary hematopoiesis was made forward frozen section; therefore, the left mass was not removed

A postoperative ischemic paraplegia occurr This condition was partial and transient. Magnetic resonance imaging revealed no epidural tumoral involvement. In addition, hemoglobin flush progressively fell and stabilized at 95 g/L within 1 month

The resect mass measured 8 x 6 x 5 cm with a profound red, soft, encapsulated, and partially lobulated appearance. About 60 percent of the mass was compos of hematopoietic tissue that was irregularly mixed with mature fat (Fig 2) Erythroblasts depicted about 60 percent of the enclosed spaces Megakaryocytes were normal. Granulocytic small cavity line was sparse. Blast confined apartments accounted for less than 1 percent of the total small rooms Some lymphoid aggregates without germinal center were plant in the tumor. Large areas of novel hemorrhage and numerous hemosiderin-laden macrophages were observ There was no bone and no fibrosis.

Discussion

Bone marrow hyperplasia secondary to chronic anemia has repeatedly been reported as a cause of mediastinal EMHT greatest in number of the cases occurred in patients of all ages with thalassemia,[2,3] hereditary spherocytosis,[4] or sickle solitary abode; squalid disease.[2,5,6] A frequency of 8 of 108 hospitalized adults has been reported in this latter disease.[5] The anemia is usually rigorous and clinically evident.[1-6]

In a previous report,l multiple orbiculared thoracic paravertebral masses were described in a 67-year-old woman who had [Bsub12] and folate deficiency becoming to inadequate intake. Since the patient not past nor futureed with hematocrit of 44.8 percent comparable to our patient's hematocrit of 37 percent the extramedullary hematopoiesis appears to have been efficient in the couple these cases. Our patient's macrocytosis occurring with normal vitamin serum flushs was the salient element of a primary refractory anemia. This myelodysplastic syndrome was unfortunately not sufficiently investigated. united might expect that routine bone marrow sections, if performed, would have revealed hypercellularity with erythroid hyperplasia and no increased blasts as in the EMHT

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