Intrathoracic Desmoid Tumor Mimicking Pleural Mass: A Case Report

Tuberc Respir Dis 2009;67:449-453

CopyrightⒸ2009. The Korean Academy of Tuberculosis and Respiratory Diseases. All rights reserved.

Intrathoracic Desmoid Tumor Mimicking Pleural Mass: A Case Report

Departments of

Pathology,

Thoracic Surgery,

Internal Medicine, Gachon University Gil Hospital, Incheon, Korea

Na Rae Kim, M.D.

, Dong-Hae Chung, M.D.

, Jae-Ik Lee, M.D.

, Sung Hwan Jeong, M.D.

, Seung-Yeon Ha, M.D.

Desmoid tumor (fibromatosis) is a histologically benign fibrous neoplasm showing locally infiltrating growth. This type of tumor commonly occurs in the abdomen, but intrathoracic desmoid tumor is uncommon. To date, 12 cases of intrathoracic desmoid tumor protruding into the pleural cavity, radiologically mimicking pleural masses, have been reported. Here, we report on a case of intrathoracic desmoid tumor protruding into the pleural cavity, and partially covered by parietal pleura. The main preoperative differential diagnoses included pleural solitary fibrous tumor, inflammatory pseudotumor or malignant mesothelioma. A near-total mass excision was performed. Pathol- ogically, the tumor was composed of a paucicellular arrangement of spindle-shaped cells with fibromyxoid stroma.

The resection margin was partially involved with spindle cells present. On histochemical staining, the spindle cells were strongly positive for vimentin and negative for CD34, consistent with a desmoid tumor. The patient was stable without further adjuvant treatment during 6-years of follow-up.

Key Words: Fibromatosis, Abdominal; Pleura

Address for correspondence: Seung-Yeon Ha, M.D.

Department of Pathology, Gachon University Gil Hospital, 1198, Guwol-dong, Namdong-gu, Incheon 405-760, Korea Phone: 82-32-460-3078, Fax: 82-32-460-3073

E-mail: [email protected] Received: Aug. 26, 2009 Accepted: Oct. 6, 2009

Introduction

Desmoid tumors are uncommon tumors accounting for less than 0.03% of all neoplasms. They show infil- trating growth of well-differentiated fibroblasts or myofi- broblasts, and tend to recur locally without metastasis

. Alternatively, the term “ aggressive fibromatosis ” has of- ten been employed to emphasize the frequently ag- gressive behavior of these tumors. Desmoid tumors are most commonly intraabdominal, and the most common extraabdominal sites include the chest wall, shoulder girdle, thigh, and head and neck. True intrathoracic des- moid tumors are rare with most cases actually represent- ing intrathoracic extension of chest wall tumors. Out of the reported intrathoracic desmoid tumors, of which a

few extended into abdominal cavities

. Twelve cases occurred in the pleura, including one Korean case

. Here, we report on a case of intrathoracic desmoid tumor protruding into the pleural cavity, and discuss its differential diagnoses along with a review of the lit- erature.

Case Report

A 40-year-old male presented with progressive and marked weight loss of 13 kg over one year and dizzi- ness for three weeks. The patient appeared to be chron- ically ill with a weight of 50 kg and height of 170 cm.

He had 30 pack years (1.5 packs per day for 20 years) and had worked in printing and handled chemicals for six years. He showed no remarkable laboratory profiles, including a normal blood glucose level. Chest com- puted tomography (CT) revealed an oval mass of 2.0 cm in size in the left upper anterior field (Figure 1).

At the base, the tumor appeared to invade into the left

chest wall. Solitary fibrous tumor (SFT), primary or

metastatic pleural tumor was radiologically suspected.

Figure 1. A chest CT scan reveals a low density thoracic wall mass (arrows) protruding into the pleural cavity.

Figure 2. (A) Hypocellular spindle cells have small in- distinct nucleoli and weakly eosinophilic cytoplasm in the fibromyxoid backgro- und (H&E stain, ×200). (B) Spindle cells are stained with vimentin (vimentin im- munostain, ×400).

Thoracoscopic surgery using three ports was performed.

The main mass, measuring 0.5 cm, protruded into the pleural cavity with a short stalk, having a base in the left second intercostal muscle. No pleural adhesion, ef- fusion, or tumor seeding was found. Thoracoscopic near total excision of the protruded mass was per- formed. During post-operative follow up, the patient ’ s marked weight loss was proved to be ascribed to hyper- thyroidism. No additional treatment was administered.

Neither recurrence, nor metastasis was found during 6 years of follow up.

1. Pathologic findings

A needle biopsy taken from the mass by ultrasound- guidance revealed paucicellular fibrous tissue admixed with a few small capillaries. Spindle cells in the pauci- cellular fibrous tissue were immunoreactive for vimentin (V9; Dako, Glostrup, Denmark, prediluted), and neg- ative for pancytokeratin (AE1/AE3; Dako, prediluted), and CD34 (QBEnd10; Dako, prediluted).

Grossly, the excised mass measured 2.5×2.0 cm.

The external surface of the mass was smooth and glis-

tening, covered by parietal pleura. The gray-tan, trabe-

culated cut surface was homogeneously solid without

hemorrhage or necrosis. Microscopically, the mass was

composed of a hypocellular arrangement of spindle-

shaped cells in a massive collagenous background

(Figure 2A). Spindle cells had small indistinct nucleoli

and fine nuclear chromatin, and weakly eosinophilic

cytoplasm. Mitosis or necrosis was not observed. Small

capillary-sized vessels were contained in some areas. A

hemangiopericytomatous vascular arrangement was not

observed. The resection margin of the stalk was focally

involved by the spindle cells. Immunohistochemistry

was performed using an avidin-biotin peroxidase com-

plex method. The cytoplasm of the spindle cells was

strongly positive for vimentin (Figure 2B), while totally

negative for CD34, pancytokeratin, S-100 protein (poly-

clonal; Dako, prediluted), CD68 (PG-M1; Dako, pre-

diluted), muscle specific actin (HHF35; Dako, pre-

diluted), desmin (D33; Dako, prediluted), progesterone receptor (PgR636; Dako, prediluted), estrogen receptor (SP1; Dako, prediluted), and p53 (DO-7; Dako, pre- diluted). The immunohistochemical stainability of Ki-67 (MIB-1; Dako, prediluted) was investigated using a qu- antitative manual counting method i-Solution 7.5 (IMT i-Solution company, Coquitlam, Canada). Maximum Ki- 67 labeling index was less than 0.1%.

Discussion

The cause of desmoid tumor is uncertain. For patho- genesis, previous trauma including surgical scars, hor- monal factors, and genetic factors such as Gardner's syndrome or familial adenomatous polyposis have been postulated. History of trauma can be considered first due to the fact that cases of desmoid tumor in operative scars of mastectomy and thoracotomy have been re- ported

. Endocrinologic hormonal etiology has been suggested due to the fact that desmoid tumor most com- monly appears in young women during or after preg- nancy, and may regress after menopause, or after ta- moxifen treatment

. Molecular studies have revealed a high incidence of adenomatous polyposis coli (APC) and β- catenin gene mutations in desmoid tumors, re- sulting in nuclear accumulation of β-catenin proetin

. Nuclear staining patterns for β-catenin in desmoid tu- mors are shared with those of pleural SFT, suggesting that pleuropulmonary desmoid tumor and SFT might have somewhat overlapping pathogenetic pathways.

In pathologic differential diagnoses of intrathoracic desmoid tumor, pleural SFT is a primary consideration.

Pleural SFT is an uncommon but increasingly recog- nized neoplasm derived from mesenchymal cells lo- cated in the submesothelial lining of the pleural space, and usually forming a pedunculated or non-peduncu- lated tumor from the parietal or visceral pleurae

. Typi- cal pathology of pleural SFT shows a disorderly config- uration of bipolar spindle cells and collagen fibers in a pattern-less arrangement, with abundant stag-horn shaped vessels that are hemangiopericytomatous in ap- pearance. Desmoid tumor is composed of bland-look-

ing spindle shaped nuclei and keloid-like connective tis- sue, with absence of hemangiopericytomatous vessels.

Spindle cells of desmoid tumor show immunonegativi- tity for CD34 and immunopositivity for vimentin, varia- ble reactions for smooth muscle actin, S-100 protein, or desmin, whereas SFT shows characteristic dual immun- oreactivity for vimentin and CD34. Other pathologic dif- ferential diagnoses include inflammatory pseudotumor (inflammatory myofibroblastic tumor), low-grade fibro- myxoid sarcoma, malignant fibrous histiocytoma and malignant mesothelioma after needle biopsy. Inflamma- tory pseudotumor is a tumor-like mass composed of fi- brous spindle cells or granulation tissue infiltrated by in- flammatory cells. Malignant fibrous histiocytoma shows a stroriform arrangement of atypical spindle cells with occasional pleomorphic stromal cells, for which a defin- able line of differentiation has not been found. Immno- histochemically, these spindle cells are usually reactive for vimentin, α1-antitrypsin, α1-antichymotrypsin, and CD68, and vary in their reactivity for actin, desmin, and lysozyme. Malignant mesothelioma commonly appears as a diffuse extension along the pleural surface, but oc- casionally shows a localized growth pattern. Localized type mesothelioma shows epithelioid features in small areas, even in the case of a sarcomatous type of malig- nant mesothelioma. Immunohistochemically, tumor cells showing positivity for low molecular weight cytokeratin and calretinin confirm malignant mesothelioma. Low- grade fibromyxoid sarcoma is rare, and benign looking, but local recurrences are frequent. Microscopically, low- grade fibromyxoid sarcoma displays a mixture of hypo- cellular, collagen-rich areas and more cellular, myxoid areas. Whorling growth patterns of spindle cells are helpful in the distinction from desmoid tumor.

Review of the previously reported thirteen cases of

intrathoracic pleural desmoid tumors including the pres-

ent case showed a preponderance of females (8 females

vs. 5 males)

. Age ranged 5 to 72 years. The size of

intrathoracic pleural desmoid tumors ranged from 2.0

cm up to 16.0 cm. The most common presentation was

dyspnea or shortness of breath (6/13, 46.2%), followed

by chest pain (4/13, 30.8%), abnormal chest shadow

Table 1. Clinicopathological summary of intrathoracic desmoid tumors including the present case

Case Age (yr), Trauma Outcome (duration

Ref. Symptoms Size (cm) Radiology Treatment

no. sex history of follow up)

3 1 14, F Dyspnea Absent 3.0 cm Hypointense on STR Not recorded

T1WI

4 2 9, M Abnormal shadow Absent Not Chest wall with rib STR, RT Not recorded recorded destruction

5 3 16, F Shortness of breath Absent 16.0 cm Rt, Lt posterior STR, RT Lost to follow up chest wall mass

4 49, M Chest pain, cough Present 12.0 cm Rt paravertebral GTR NED (8 yr) mass

5 66, M Chest pain Present 5.0 cm Rt lung GTR NED (1 yr)

6 45, F Shortness of breath, Absent 7.0 cm Lt apical thorax STR SRD (1 yr) chest pain

6 7 46, F Abnormal shadow Absent 13.0 cm Lesion of the left STR SRD (2.7 yr) parietal pleura

7 8 21, F Left shoulder and Absent 5.5 cm Left parietal pleura GTR, RT 1st recurrence

arm pain (1st recurrence), (9 mo), 2nd

tamoxifen (2nd recurrence recurrence) (3 mo) 8 9 60/F Chest and flank pain, Absent 3.5 cm Right apical parietal GTR Not recorded

shortness of breath pleura

9 10 42, F Shortness of breath Absent 11.0 cm Right thoracic mass GTR, tamoxifen NED (18 mo) 10 11 72, F Dyspnea, flank and Absent 8.0 cm Right thoracic mass GTR Not recorded

back pain

11 12 5, M Not recorded Not 5.6 cm Not recorded Not recorded Not recorded

recorded

The 13 40, M Weight loss, Absent 2.0 cm Pleura-protruding Near GTR NED (6 yr)

pre- dizziness due to mass having a short

sent hyperthyroidism base at the intercos-

case tal muscle

Ref: number of reference; M: male; F: female; Rt: right; Lt: left; GTR: gross total resection; STR: subtotal resection; RT: radiation therapy; FU: follow up; SRD: stable with residual disease; NED: no evidence of disease.

(4/13, 30.8%) and cough (2/13, 15.4%), flank or back pain (2/13, 15.4%), shoulder and arm pain (1/13, 7.7%).

Radiologic findings show desmoid tumor variability;

high signal intensity on T2-weighted images and low to isointensity on T1-weighted images with respect to mus- cle

. These nonspecific clinicoradiologic features shar- ed with those of the more common pleural SFT. The present case showed severe weight loss and dizziness, but were caused by incidentally accompanying hyper- thyroidism. Clinicoradiologic summaries are shown in Table 1.

Treatment of intrathoracic desmoid tumor is challeng- ing because this disease does not respect the usual sur- gical rules relating to resection and recurrence. Com-

plete excision with clear margins is the mainstay of

treatment. Due to the high local recurrence rate, ad-

juvant therapy may be conducted. Radiotherapy has

been traditionally directed at known positive margins

and in inoperable cases. Antiestrogen hormone therapy

and cytotoxic chemotherapy have also been used for

unresectable or recurrent disease, however, such experi-

ences have been limited, and results have been incon-

clusive

. Like extraabdominal desmoid tumor of other

sites, the natural course of intrathoracic desmoid tumor

is widely variable, ranging from spontaneous remission

to multiple recurrences, regardless of treatment modal-

ity

. Adjuvant radiotherapy can be reserved for the mi-

nority with a high risk of recurrence, particularly those

with residual bulk disease or multiple previous recur- rences. Despite controversies over adjuvant therapy, a desmoid tumor in an unusual location, preventing wide excision margins, may favor early consideration of ad- juvant therapy, particularly in premenopausal women.

Albeit rare, malignant transformation of extra-abdominal desmoid tumor may occur

. To date, no malignant trans- formation, including that of pleural mass, has been de- scribed among intrathoracic cases. The present case was focally involved by the tumor with no recurrence during the follow up period, suggesting pleural desmoid tu- mors might take more favorable prognosis than do non- pleural desmoid tumors. Due to lack of accumulated ex- perience, intrathoracic desmoid tumors, including pleu- ral masses, should be under long term follow-up.

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