Pulmonary Carcinoid With Papillary Structure: Report of a Case With Fine-Needle Aspiration Cytology Hilary Evans, M.D., F.I.A.c., and Ronald Blaney, S.C.T. (A.S.C.P.)

Fine-needle aspiration biopsy of a peripheral lung mass in a 44-yr- old man revealed apapillary tumor. Histologic examination of the mass, removed by lobectomy, demonstrated a pulmonary carci- noid tumor with papillary structure. Most papillary tumors of the lung are malignant. Pulmonary carcinoid and pulmonary scleros- ing hemangioma-benign tumors-have papillary variants. Both have been described in jine-needle aspiration specimens and should be included in the drflerential diagnosis of papillary lung tumors. The cytologic features of pulmonary carcinoid are de- scribed. Diagn Cytopathol 1994;11:178-181. @ 1994 Wiley-Liss, Inc.

At thoracotomy, the tumor was in the left lower lobe, posteriorly. Left lower lobectomy was performed. The postoperative course was uneventful. The patient is now asymptomatic, 2 yr after surgery.

Key Words: Carcinoid tumors; Lung neoplasms; FNAB

Peripheral lung masses are usually diagnosed by percu- taneous transthoracic fine-needle aspiration biopsy (FNAB), because they are inaccessible to the broncho- scope. Carcinoid tumors are rare in the periphery of the lung, 90% being central. Peripheral carcinoids-those distal to segmental bronchi-more often have unusual features. As a distinct subset of lung tumors, peripheral carcinoids present a diagnostic challenge to the cytopa- thologist. We report a patient in whom a peripheral pul- monary carcinoid had papillary structure.

Case Report A 44-yr-old man who was a heavy smoker (20-25 pack years) complained of vague discomfort in the left anterior chest. Roentgenographic examination demonstrated a 4 cm density posterior to the left pulmonary hilum. After a negative bronchoscopy, transthoracic FNAB revealed a papillary neoplasm.

Received August 26, 1993. Accepted December 7, 1993. From the Department of Pathology, Lee Hospital, Johnstown, PA. Address reprint requests to Hilary Evans, M.D., F.I.A.C., Depart-

ment of Pathology, Lee Hospital, 320 Main Street, Johnstown, PA 1 590 1 - 1694.

Fig. 1. Aspirate of the lung lesion reveals a papillary neoplasm (Papanicolaou stain, x 100).

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Fig. 2. Cuboidal to low columnar cells with bland nuclei and an order]y growth pattern are supported by a loose fibrovascular (papanico- laou stain, ~400).

Fig. 3. Cells more typical ofcarcinoid tend to form small syncytia. They have fairly uniform nuclei, fine chromatin, and delicate cytoplasm with indistinct cell borders (Papanicolaou stain, x 400).

Cytologic Findings Papillary structures, in which cuboidal to low columnar cells were supported on a fibrovascular core, were the most prominent cytologic finding (Figs. 1,2). Between the papillary structures were clusters of cells more typical of carcinoid (Fig. 3). They had round-to-oval, fairly uniform nuclei with finely granular chromatin, and one to three chromocenters. An occasional nucleus contained a small nucleolus. The cytoplasm was wispy and amphophilic. Cell borders were indistinct, and there was a tendency to form syncytia.

Gross Findings The surgical specimen was a left lower lobe of lung. Im- mediately beneath the pleura, but not attached to it, was a 3.5 cm diameter, well-circumscribed, round, firm gray

mass. The tumor was not associated with a bronchus. The rest of the lung parenchyma, as well as the pleura, bronchi, vessels, and bronchial lymph nodes were unre- markable.

Microscopic Findings The tumor was composed of papillary (Fig. 4) and solid areas (Fig. 5). The papillary portions of the tumor had the same structure as seen in the FNAB smears. The solid portions tended to form pseudorosettes, in which tumor cells in acinar formation surrounded a capillary.

The individual cells were typical for carcinoid: uniform cuboidal to low columnar cells with abundant finely gran- ular amphophilic cytoplasm, distinct cell borders, and round-to-oval nuclei with fine chromatin. Grimelius stain demonstrated argyrophil granules in the cytoplasm of tumor cells.

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Fig. 4. Histologic section of the tumor shows richly vascular papillary structures (H&E, X 100).

Fig, 5. Solid portions of the tumor show typical carcinoid cells, arranged around capillaries (H&E, x 400).

Discussion Four papillary carcinoid tumors of the lung have been reported. 4-7 Two were peripheral, 4,5 one was located in a segmental bronchus,6 and in one the location is not gi- ven. The two peripheral tumors were diagnosed preoper- atively by percutaneous transthoracic FNAB, but the cy- tology is not illustrated.

Capillaries are prominent within the supporting stroma of the papillary structures in the tumor presented here. Recently, capillaries have been described as an important diagnostic feature in both bronchial brushing and FNAB specimens of pulmonary carcinoid tumors. * Rich vascu- larity has long been a recognized histologic feature of pulmonary carcinoid. Clinically this is manifested by a tendency to bleed on bronchoscopic biopsy.

Carcinoid is not within the usual differential diagnosis of papillary lung tumors, virtually all of which are malig- nant: papillary adenocarcinoma; bronchioalveolar carci- noma; metastatic adenocarcinoma from ovary, thyroid, breast, colon, or pancreas; malignant mesothelioma; pul- monary blastoma. Two benign lung tumors-carcinoid

and sclerosing hemangioma-can have papillary struc- ture. 5,10

When a pulmonary carcinoid tumor has papillary struc- ture, the differential diagnosis from the malignant papil- lary tumors depends upon the greater depth of focus of malignant papillae and upon the pleomorphic nuclei of malignant cells.

Pulmonary carcinoid tumor and sclerosing hemangi- oma can strongly resemble each other in FNAB material. One sclerosing hemangioma has been misdiagnosed as carcinoid by aspiration cytology. Review of the case in comparison with pulmonary carcinoids revealed only sub- tle differences: more cohesion and better preserved cyto- plasm in sclerosing hemangioma. '' As only two pulmo- nary sclerosing hemangiomas diagnosed preoperatively by FNAB have been reported, one cannot confidently state differential diagnostic criteria.

In summary, papillary carcinoid tumor of the lung must be differentiated from the more common papillary lung tumors, most of which are malignant.

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Note Added in Proof Since the submission of this article, a third pulmonary sclerosing hemangioma, with papillary/sclerotic struc- ture, examined by FNAB, has been reported. The case is a significant contribution to the small literature on the cytology of benign papillary lung tumors. l 3

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