J Rhinol > Volume 27(2); 2020
Cheong, Kim, and Choi: Melanotic Oncocytic Metaplasia of the Nasopharynx in the Patient with Suspicious Hemoptysis: Case Report

Abstract

Melanotic oncocytic metaplasia (MOM) in the nasopharyngeal space is a very rare entity. Only 35 cases have been reported in the English literature, and most patients were East Asian males between 60 and 70 years of age. MOM presents as a brown or black lesion with slight elevation of the mucosa. These lesions are benign and defined as cellular enlargement with eosinophilic granular melanin-pigmented cytoplasm caused by mitochondrial accumulation. However, such presentation can lead physicians to misjudge MOM as a malignant lesion. Recently, we experienced a case of MOM of the nasopharynx. A 58-year-old woman was admitted to the internal medicine department with small-volume hemoptysis and referred to the ENT department for evaluation. She was a regular smoker without any medical history. Sinus endoscopy showed black pigmented lesions on both the torus tubaris and left posterior tonsillar pillar, with low bleeding risk. Excisional biopsy of the lesion was performed, and oncocytic metaplasia was confirmed pathologically. Hemoptysis showed spontaneous remission and no recurrence or other symptoms over 12 months of follow up. Melanotic oncocytic metaplasia in the nasopharynx should be clinically recognized to avoid misdiagnosis as a malignancy like melanoma.

INTRODUCTION

First melanotic oncocytic metaplasia (MOM) of the nasopharynx was reported in 1995 [1]. MOM can be misdiagnosed as early nasopharyngeal carcinoma or melanoma, due to its macroscopic appearance. However, MOM is clearly distinct from such diseases histologically. MOM comprises both oncocytic metaplasia and melanin pigmentation of the epithelium in the same gland. Oncocytes are big epithelial cells with an aplenty, deeply eosinophilic granular cytoplasm and a small, round, dark colored nucleus. Melanocytes found to coexist in MOM, is considered to be the source of melanin [2]. No atypia or mitotic activity found in MOM. Fontana-Masson staining is positive and highlights several dendritic melanocytes between the metaplastic and the surface epithelial cells [3]. MOM is thought to be an age-related change since its incidence increases with age, and predominantly occurs in Asian population [4].
MOM of the nasopharynx is a very rare lesion, and only 35 cases were reported in English literature. Most lesions were asymptomatic and incidentally discovered during physical examination.
We present here a case of MOM of the nasopharynx, found in a patient with suspicious hemoptysis.

CASE REPORT

A 58-year-old woman was admitted to internal medicine department, presenting small volume hemoptysis for 5 days. She was a regular smoker (10/day×20 years) without any medical history. Patient admitted and undergone computed tomography scan of lung. Since the radiologic evaluation at the internal medicine department showed no clinical significance except for minor bronchopneumonia, consultation to ENT department was proceed for further evaluation of other possible causes. Sinus endoscopy revealed black pigmented lesions on both torus tubaris and left posterior tonsillar pillar (Fig. 1), but bleeding from the lesion was unseen. Sinus mucosa and anatomy was intact otherwise. Though hemoptysis stopped spontaneously during the admission period, surgical biopsy of the lesion was performed to rule out possible malignancy. Five specimens were sent for hematoxylin and eosin(H&E) staining. Microscopically, homogenous oncocytic cells with melanin pigment granules in their cytoplasm were found, and melanotic oncocytic metaplasia was pathologically confirmed (Fig. 2). Hemoptysis stopped spontaneously. The patient discharged without complications and didn’t presented hemoptysis or other symptoms during 12 months follow up. Endoscopic finding showed no further growth or advancement of previous lesion (Fig. 3).

DISCUSSION

Oncocytic change found in the upper respiratory tract is an unusual finding. Melanotic variation of oncocytic metaplasia is an extremely anomalous condition, presented as a small, brown to black mucosal lesion [3]. To our knowledge, only 35 cases have been reported in the English literature, and our case is the 36th (Table 1). All reported cases were elderly Asian, supporting the possibility of ethnic background as a predisposing factor of MOM. MOM predominantly occurred in males (31/36), and most of patients were long time smoker (18/19), supporting the hypothesis that smoking might be a predisposing factor for MOM. The male predominance of patients supports this hypothesis also, since male smokers are more frequent among Asian population. 16 cases showed single lesion while other 20 cases presented multiple lesions in nasopharynx. The presented patient was an Asian female with multiple lesions, and smoking history was relatively short compared to other 17 previously reported cases with smoking history.
Pathological findings of the patient in H&E stain showed oncocytic metaplasia and scattered melanin pigment granules. Atypia or mitotic figures were not found. Oncocytic cells are epithelial cells, characterized by abundant eosinophilic cytoplasm. Yet, oncocytic metaplasia is uncommon finding in upper respiratory tract. The exact origin of the melanin pigment in MOM is still in question. However, previous studies demonstrated that Fontana-Masson stain, S-100 protein immunostain and human melanoma black-45 immunostain revealed dendritic melanocytes stretching through the epithelial cells of the glands in MOM [2,9], supporting that melanin pigment may be derived from the adjoining melanocytes through their stretching dendrites [6,14].
Most of the cases were found incidentally with other symptoms such as tinnitus, hoarseness, epistaxis, rhinorrhea, and hemoptysis. Some symptoms, such as ear discomfort at the same side of MOM near eustachian opening, seemed to be related with the lesion, while other symptoms like hoarseness seemed almost independent from the lesion.
It is unclear whether MOM can cause hemoptysis or not. One case with hemoptysis was reported previously [9], but it’s clinical course or relation between the lesion was not described. Three cases with epistaxis had been reported also. During the endoscopic biopsy of presented case, the lesions didn’t show hemorrhagic features, supporting irrelevance between hemoptysis and the lesion. Minor bronchopneumonia could have been the origin of hemoptysis in this case, but was not clearly identified.
Clinically, carcinoma or melanoma may show similar appearance with MOM during the endoscopic examination. Differential diagnosis between those entities are straightforward histologically, so physicians encountered such lesions should try biopsy. Endoscopic findings isn’t sufficient to distinguish between MOM and nasopharyngeal malignancy since nasopharyngeal malignancy may shows various forms including submucosal lesions.
It is known that MOM follows a benign clinical path. Simple excision is a suitable treatment for MOM [2]. No abnormal bleeding or surgical difficulty was found in operation of this case. Since no recurrence or advancement of the lesion has been reported in the literatures, diagnosed MOM can be observed without any further treatment.
In conclusion, we report the 36th cases of melanotic oncocytic metaplasia in the nasopharynx. As a benign imitator of malignant lesion, MOM should be always taken into consideration in examination of nasopharynx.

Fig. 1.
Endoscopic findings. A: Endoscopic finding of melanotic oncocytic metaplasia on left anterior pharyngeal pillar (white arrow). B: Endoscopic finding of melanotic oncocytic metaplasia on both torus tubaris (white dotted arrows).
jr-2020-00330f1.jpg
Fig. 2.
Pathologic results of the case. A: Microscopic finding (×100) shows deeply homogeneous eosinophilic epitheial cells, noted with lumen formation. B: Scattered melanin pigment granules are found in eosinophilic cytoplasm (×400).
jr-2020-00330f2.jpg
Fig. 3.
Endoscopic findings after 12 months. A: Rt torus tubaris. B: Lt torus tubaris.
jr-2020-00330f3.jpg
Table 1.
Reported cases of melanotic oncocytic metaplasia of nasopharynx
Case Sex/age Site Chief complaint for visiting clinic Number of lesions Smoking history Author/year
1 M/67 EO Otitis media Single Unknown Shek TW, 1995 [1]
2 M/63 EO Tinnitus Single Unknown Shek TW, 1995
3 M/70 Bilateral EO Tinnitus Multiple Unknown Xue WC, 1999 [5]
4 M/64 Bilateral EO, left suprapharynx, and nasal cavity Throat discomfort Multiple Unknown Hirakawa E, 1999 [6]
5 M/62 Left EO and bilateral torus tubaris Discomfort in Lt ear Multiple Unknown Takano K, 2004 [7]
6 M/69 Left nasopharynx Foreign body swallowing Multiple Unknown Kurihara K, 1997 [8]
7 M/80 Right nasal cavity and pharynx Hoarseness Multiple 10/day×50 yr Sakaki M, 2004 [9]
8 M/69 Left EO Hoarseness Single 40/day×60 yr Sakaki M, 2004
9 M/74 Left nasopharynx Rhinorrhea Single Unknown Sakaki M, 2004
10 F/74 Right EO Throat discomfort Multiple Unknown Sakaki M, 2004
11 M/68 Nasopharynx None Single Unknown Sakaki M, 2004
12 M/65 Right EO Hemoptysis Single Unknown Sakaki M, 2004
13 M/63 Left EO Epistaxis Single Unknown Sakaki M, 2004
14 M/- Bilateral nasopharynx None(examined to find origin site of metastatic carcinoma) Multiple Unknown Liao C, 2005 [10]
15 M/79 Right EO Otitis media Single 20/day×40 yr Lui PC, 2004 [11]
16 M/58 Bilateral nasopharynx Epistaxis Multiple Unknown Li Y, 2010 [12]
17 M/73 Bilateral torus tubaris Nasal congestion Multiple Non-smoker Kondo, 2010 [13]
18 M/72 Bilateral torus tubaris Headache and hearing Multiple 40/day×50 yr JY Na, 2012 [14]
19 M/71 Left torus tubaris and soft palate Hoarseness Multiple 20/day×40 yr JY Na, 2012
20 M/51 Right torus tubaris Tongue pain Multiple Unknown JY Na, 2012
21 M/63 Nasopharynx Epistaxis Multiple 40/day×40 yr Chang, 2014 [15]
22 M/57 Right torus tubaris None (examined to find origin site of metastatic carcinoma) Multiple 30/day×40 yr Shogo Tajima, 2015 [2]
23 F/70 EO Routine gastrointestinal endoscopy Multiple Unknown Uehara K, 2015 [16]
24 F/61 Left EO Hoarseness Single Unknown Uehara K, 2015
25 M/74 Bilateral nasopharynx Hoarseness Multiple Unknown Uehara K, 2015
26 M/57 Right nasopharynx Nasal obstruction Single Smoker Li J, 2019 [17]
27 M/61 Left nasopharynx Neck mass Single Smoker Li J, 2019
28 M/69 Left nasopharynx Rhinorrhea Multiple Smoker Li J, 2019
29 M/56 Left EO Epistaxis Single Smoker Li J, 2019
30 M/58 Right nasopharynx Facial palsy Single Smoker Li J, 2019
31 M/52 Left EO Tinnitus Multiple Smoker Li J, 2019
32 F/77 Left nasopharynx Hoarseness Single Smoker Li J, 2019
33 M/59 Left nasopharynx Nasal obstruction Single Smoker Li J, 2019
34 M/59 Left EO Tinnitus Single Smoker Li J, 2019
35 M/75 Right EO Epistaxis Multiple 30/day×50 yr Chen HY, 2020 [18]
36 F/53 Left posterior tonsillar pillar, both torus tubaris Hemoptysis Multiple 10/day×20 yr Present case, 2020

EO: Eustachian opening, M: male, F: Female

References

1) Shek TWH, Luk ISC, Nicholls JM, Fok KO. Melanotic oncocytic metaplasia of the nasopharynx. Histopathology 1995;26(3):273–5.
crossref pmid
2) Tajima S, Ohkubo A, Yoshida M, Koda K, Nameki I. Melanotic oncocytic metaplasia of the nasopharynx: a case report with a focus on immunohistochemical analyses and literature review. International Journal of Clinical and Experimental Pathology 2015;8(2):2103–10.
pmid pmc
3) Antonio C, Pieter J, Nina G, Alessandro F. Pathology of the Head and Neck. 2nd ed; Berlin, Heidelberg: Springer; 2016.

4) Mills S. Histology for Pathologists Philadelphia: Lipincott Williams & Wilkins; 2012.

5) Xue WC, Hui YZ. Melanotic oncocytic metaplasia of the nasopharynx. Histopathology 1999;35(5):481–2.
crossref pmid
6) Hirakawa E, Miki H, Ohmori M, Kobayashi S, Haba R, Nagai Y. Melanin pigmented oncocytic metaplasia of the nasopharynx. Virchows Archiv 1999;434(5):455–7.
crossref pmid
7) Takano KI, Sato J, Shirasaki H, Yamazaki N, Hoki K, Himi T. Melanin pigmented oncocytic metaplasia of the nasopharynx. Auris Nasus Larynx 2004;31(2):161–3.
crossref pmid
8) Kurihara K, Nakagawa K. Pigmented variant of benign oncocytic lesion of the pharynx. Pathology International 1997;47(5):315–7.
crossref pmid
9) Sakaki M, Shek TWH, Hirokawa M, Kashima K, Daa T, Gamachi A, et al. Melanotic oncocytic metaplasia of the nasopharynx: a report of seven cases and review of the literature. Virchows Archiv 2004;444(4):345–9.
crossref pmid
10) Liao CT, Kuo TT. Melanotic Oncocytic Metaplasia of the Nasopharynx. International Journal of Surgical Pathology 2005;13(3):279.
crossref pmid
11) Lui PCW, Chan ABW, Chan KF, Choi CH, Tse GMK. Melanocytic and non-melanocytic oncocytic metaplasia of the nasopharynx. Pathology 2004;36(5):504–5.
crossref pmid
12) Li Y, Lu ZH, Lü W, Chen J. Images for diagnosis. Melanotic oncocytic metaplasia of nasopharynx: a case report with review. Chin Med J (Engl) 2010;123(9):1230–2.
pmid
13) Kondo T, Mori K, Oka S, Morinaka S. Melanotic oncocytic metaplasia of the nasopharynx as a benign mimicker of malignant melanoma: a case report. Diagnostic Pathology 2010;5:5.
crossref pmid pmc
14) Na JY, Kim YH, Choi YD, Lee JS. Melanotic oncocytic metaplasia of the nasopharynx: a report of three cases and review of the literature. Korean Journal of Pathology 2012;46(2):201–4.
crossref pmid pmc
15) Chang IW, Wang CC, Liu KW, Lan CH, Hung CH. Melanotic oncocytic metaplasia of the nasopharynx. Polish Journal of Pathology 2014;65(2):162–5.
crossref pmid
16) Uehara K, Usami Y, Imai Y, Shimizu M. Melanotic oncocytic metaplasia of the nasopharynx. Pathology International 2015;65(3):144–7.
crossref pmid
17) Li JJX, Ng JKM, Chan ABW. Clinicopathological features of melanotic and non-melanotic oncocytic lesions of the nasopharynx. Pathology 2019;51(6):600–4.
crossref pmid
18) Chen HY, Gule MF, Chang IW. Melanotic oncocytic metaplasia of the nasopharynx: a case report with review of literature. Ear Nose Throat J 2020;145561320907427.
crossref
TOOLS
METRICS Graph View
  • 0 Crossref
  •  0 Scopus
  • 598 View
  • 11 Download
Related articles


Editorial Office
101 Hyundai ESA Apt., 20, Hyoryeong-ro 77-gil, Seocho-gu, Seoul 06628, Republic of Korea
Tel: +82-2-3461-9945    Fax: +82-2-3461-9947    E-mail: shcho@hanyang.ac.kr                

Copyright © 2021 by Korean Rhinologic Society. All rights reserved.

Developed in M2PI

Close layer
prev next