A PROSPECTIVE STUDY ON CLINICAL PREDICTORS IN
DIAGNOSING BENIGN SUPERFICIAL SOFT TISSUE MASSES SEEN AT OSPITAL NG MAYNILA
MEDICAL CENTER SURGERY-OUT PATIENT DEPARTMENT FROM MAY TO AUGUST 2006
Edwin
P. Estonilo, MD Department of Surgery, Ospital
ng Maynila, Medical Center,
Quirino Ave, Malate Manila,
Philippines.
Edgardo Penserga, MD.FPCS FPSGS
Reynaldo
O. Joson, MD, MHA, MHPEd,
MS Surg
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ABSTRACT
This is a prospective study that
would validate the diagnostic value of a good physical
examination in assessing patients with superficial masses. Patients
with benign superficial tissue masses seen at Ospital
ng Maynila Medical Center
(OMMC), Surgery - Out Patient Department (OPD) from May to August 2006 were
evaluated according to certain parameters such as presence of punctum, relation of the mass to the overlying skin,
consistency, delineation of borders, history of inflammation and presence of
discharge. Validity and reliability of the parameters used were analyzed using
the sensitivity and specificity of the test and positive and negative
predictive values, respectively.
Using simple random sampling, 112 patients with palpable superficial masses were
evaluated at OMMC- Surgery-OPD from May to August 2006. Seventy two percent (n= 81) of whom were
initially diagnosed with epidermal inclusion cyst and 28% (n= 31) were
diagnosed with lipoma.
The probability that the superficial tissue mass is an epidermal
inclusion cyst based on physical findings would include in descending order: punctum, consistency and delineable border. Presence of history of infection and presence
of discharge is not a reliable criterion to diagnose such disease. Moreover, the probability of diagnosing lipoma based on physical findings would be low using
parameters such as tethered to skin and presence of punctum
and a higher probability in diagnosing lipoma in
tumors presenting with soft, barely delineable borders.
INTRODUCTION
Benign skin tumors are commonly seen by any physicians. We frequently encounter patients with
dermatologic diseases, either as the primary complaint or as a "by the
way." To a patient with an unknown
mass or tumor, we as surgeons are often consulted first amongst other
specialists. The ability to properly diagnose and treat common benign tumors
and to distinguish them from one lesion to another is a vital skill for all
physicians. Diagnosis usually is based on the appearance of the lesion and the
patient's clinical history, although biopsy is sometimes required.
Several different terms
have been used to describe epidermal cysts. Epidermal inclusion cyst (EIC)
refers to those cysts that are the result of the implantation of epidermal
elements in the dermis. However, many cysts originate from the infundibular portion of the hair follicle, and the more
general term, epidermoid cyst, is favored. Sebaceous
cyst is a misnomer, and the term should not be used at all because these cysts
are not of sebaceous origin.
Lipomas
are the most common soft tissue tumor. These slow-growing, benign fatty tumors
form lobulated soft masses enclosed by a thin fibrous
capsule. Although it has been hypothesized that lipomas
may rarely undergo sarcomatous change, this event has
never been convincingly documented. It is more probable that lipomas are at the benign end of the spectrum of tumors,
which, at the malignant end, include liposarcomas.
Because more than half of lipomas encountered by
clinicians are subcutaneous in location, most of this article will be devoted
to that subgroup. Additional information about other locations (eg, intramuscular, retroperitoneal, gastrointestinal) will
be included as appropriate.
In Ospital
ng Maynila Medical Center
(OMMC), the Department of Surgery has been adopting a selective pre-operative
screening since 2002. The department utilized clinical evaluation, good history
taking and thorough physical examination that would enable a clinician to
decide if patient still needs additional paraclinical
diagnostic examination.
In this study,
diagnosis of certain benign soft tissue tumors specifically lipoma
and epidermal inclusion cysts based on some physical characteristics was
tested. Characteristics were based on the presence or absence of a punctum, whether a tumor is fixed to the overlying skin,
color, consistency, borders of the mass, presence or absence of
inflammation/discharge.
OBJECTIVES
General:
To validate the diagnostic value of a good physical examination in
assessing patients with benign superficial masses specifically epidermal
inclusion cyst and lipoma.
Specific objectives:
To correlate the clinical picture of
patient presenting with benign superficial masses
METHODOLOGY
Design: Prospective study of
cases from May to August 2006
Setting: Ospital ng
Inclusion Criteria:
All patients seen from May to August 2006 who came
in at OMMC Surgery-OPD presenting with palpable superficial mass.
This is a prospective study of
patients with benign superficial tissue masses seen at Ospital
ng Maynila Medical Center
(OMMC), Surgery - Out Patient Department (OPD) on May 2006. Patients with
palpable superficial masses were thoroughly examined.
Parameters such as presence or
absence of punctum and the relation of the mass to
the overlying skin were noted.
Consistency as to firm or soft and delineation of borders whether well
defined or barely defined were also evaluated. Presence or absence of history
of inflammation and presence or absence of discharge was also examined.
Patients were evaluated by any surgical
resident assigned at the OMMC Surgery-OPD on the said span of time.
Validity and reliability of the
parameters used were analyzed using the sensitivity and specificity of the test
and positive and negative predictive values, respectively.
DEFINITION OF TERMS
Punctum- a minute round spot differing in color or
appearance from the surrounding tissues
Well-defined border-
border of a palpable superficial mass with regular
boundaries
Barely defined border- border of a palpable
superficial mass with irregular boundaries.
Sensitivity of the Test- probability
of a positive test among patients with disease
Specificity of the Test-
probability of a negative test among patients without disease
Positive Predictive Value- probability that a person with a positive test result actually has the
disease
Negative Predictive Value- probability that a person with a negative result actually doesn’t have
the disease
RESULT
Using simple random
sampling, 112 patients
with palpable superficial masses specifically epidermal inclusion cyst and lipoma were evaluated at OMMC- Surgery-OPD from May to
August 2006. Seventy two percent (n= 81)
and 28% (n= 31) of whom were diagnosed with epidermal inclusion cyst and lipoma, respectively.
Figure 1. Percentage of patients with epidermal inclusion cyst and lipoma seen at OMMC- Surgery-OPD from May to August 2006.
Epidermoid cysts grow slowly and usually do not cause symptoms, but they may
become inflamed or secondarily infected, resulting in pain and tenderness. In
one study, epidermoid cysts were approximately twice
as common in men as in women. Epidermoid cysts may
occur at any time in life, but they are most common in the third and fourth
decades of life.
|
Epidermal Inclusion
Cyst |
Presence of Punctum |
Absence of Punctum |
|
Positive for EIC |
70 |
11 |
|
Negative for EIC |
0 |
31 |
Table 1. Number of
patients diagnosed with epidermal inclusion cyst as to punctum
Out of 81 patients diagnosed with epidermal inclusion cyst, 70 of whom
were presented with punctum on the superficial
tissue mass and 11 have none. The presence of punctum
used as a criterion to diagnose epidermal inclusion cyst would yield a
sensitivity of 100% and specificity of 26%.
Positive Predictive Value and Negative Predicitive Value yields to 86% and 100%, respectively. Therefore, presence of punctum
in patients with soft tissue mass could be a good physical exam parameter to
rule in epidermal inclusion cyst, however based on one study, a central pore or
punctum is an inconsistent finding (Brown, 2001).
In
contradiction with lipoma, a very low positive
predictive value of 0% and sensitivity test of 0% shows that presence of punctum is not a good parameter to diagnose lipoma. This
actually differentiates lipoma with epidermal
inclusion cyst in which its presence is consistent with the latter.
|
Lipoma |
Presence
of Pumctum |
Absence
of punctum |
|
Positive
for lipoma |
0 |
31 |
|
Negative
for lipoma |
70 |
11 |
Table 7. Number of patients diagnosed with lipoma as to punctum
Epidermal Inclusion Cysts are nodules that are freely movable over
underlying tissue and are attached to the normal skin above them by the remain of the expanded gland duct (Domonkos,
1982). Based on this study, 73 of
patients with EIC were presented with superficial tissue mass tethered to skin
and 8 are not. This would yield a
sensitivity of 100% and specificity of 79% and would predict a Positive
Predictive Value and Negative Predicitive Value
yields to 90% and 100%, respectively.
According to Behrman, 1992, epidermal
inclusion cyst are usually freely movable in contrast to the above finding
which shows a high positive predictive value, hence could be used as a good
physical parameter to diagnose such disease.
Table 2.
Number of patients diagnosed with epidermal inclusion cyst as to
tethered to skin
|
Epidermal Inclusion Cyst |
Tethered to Skin |
Not tethered to skin |
|
Positive for EIC |
73 |
8 |
|
Negative for EIC |
0 |
31 |
These findings also hold true to lipoma in
which there is a low positive predictive value and sensitivity value of both 0%. Therefore, this is a not a good parameter to
indicate the said disease. According to Cribb, 2005, a characteristic
“slippage sign” may be elicited by gently sliding the fingers off the edge of
the tumor. The tumor will be felt to slip out from under, as opposed to a
sebaceous cyst or an abscess that is tethered by surrounding induration.
Table8. Number of patients diagnosed with lipoma as to Tethered to skin
|
Lipoma |
Tethered to Skin |
Not Tethered to skin |
|
Positive for Lipoma |
0 |
31 |
|
Negative for Lipoma |
73 |
8 |
Seventy-two out of 81 patients with Epidermal
inclusion cyst exhibited with firm nodules while 9 patients presented with soft
nodules. This shows a high sensitivity
test of 94% and a specificity test of 74%. Positive predictive value of 89%
confirms that a firm consistency of a superficial mass could be a screening
examination for a positive epidermal inclusion cyst.
Table 3.
Number of patients diagnosed with epidermal inclusion cyst as to
consistency
|
Epidermal Inclusion Cyst |
Well-defined |
Barely defined |
|
Positive for EIC |
71 |
10 |
|
Negative for EIC |
5 |
26 |
Out of 81 patients diagnosed with epidermal inclusion
cyst, 71 of whom were presented with well defined border on the superficial
tissue mass and 10 are not. The presence of well defined border used as a
criterion to diagnose epidermal inclusion cyst would yield a sensitivity of 93%
and specificity of 72%. Positive Predictive Value and Negative Predicitive
Value yields to 88% and 83%, respectively.
Table4. Number of patients
diagnosed with epidermal inclusion cyst as to delineable border
|
Epidermal Inclusion Cyst |
Firm |
Soft |
|
Positive for EIC |
72 |
9 |
|
Negative for EIC |
5 |
26 |
|
Lipoma |
Well |
Barely |
|
Positive for Lipoma |
5 |
26 |
|
Negative for Lipoma |
71 |
10 |
In comparison to patients with lipoma, a low sensitivity test of 6.58% in superficial
tissue mass with well-defined borders would rule out lipoma
as a diagnosis.
Table10. Number of patients
diagnosed with lipoma as to Delineable border
Inflammation is in part mediated by the horny material
contained in epidermoid cysts. Extracts of this
material have been shown to be chemotactic for polymorphonucleocytes.
Table5. Number of patients
diagnosed with epidermal inclusion cyst as to history of infection
|
Epidermal Inclusion Cyst |
Presence of infection |
Absence of infection |
|
Positive for EIC |
19 |
62 |
|
Negative for EIC |
2 |
29 |
In
patients with epidermal inclusion cyst, 19 presented with history of
inflammation while 62 patient have none. A low positive predictive value of 23% shows
that history of inflammation in the development of epidermal inclusion cyst
would reveal that this is not a good parameter to diagnose such disease. However,
Table 11.
Number of patients diagnosed with lipoma as to
History of infection
|
Lipoma |
Presence of history of infection |
Absence of history of infection |
|
Positive for lipoma |
2 |
29 |
|
Negative for lipoma |
19 |
62 |
Findings in this study shows no significant difference compared with that
of lipoma in which, a much lower positive predictive
value of 16%. This result is consistent
with its sensitivity and specificity values of 6.58 and 28%, respectively.
Discharge of an epidermal inclusion cyst is of a foul-smelling
cheese-like material, which is usually the main chief complaint of patient
having the disease. In this study, 49% positive predictive value revealed a low
probability that the entity can be seen in patients with EIC. This is consistent with a high negative
predictive value of 100% and a high sensitivity value of 100% which would rule
out the entity as a parameter for the disease.
These findings can be attributed to the low prevalence of patients who
manifested a superficial tissue mass with discharge at the time of the study.
Table 6.
Number of patients diagnosed with epidermal inclusion cyst as to
presence of absence
of discharge
|
Epidermal Inclusion Cyst |
Presence of discharge |
Absence of discharge |
|
Positive for EIC |
4 |
77 |
|
Negative for EIC |
0 |
31 |
The same with
the findings seen in lipoma in which a 0% positive
predictive value would make this physical examination to rule out lipoma.
Table12. Number of patients diagnosed with lipoma as to presence of discharge
|
Lipoma |
Present
|
Absent |
|
Positive
forLipoma |
0 |
31 |
|
Negative
forLipoma |
4 |
77 |
DISCUSSION
The objective of this study is to provide a valid
clinical predictors of benign superficial tissue masse specifically epidermal
inclusion cyst and lipoma to aid the physicians in
predicting its nature. Commonly used parameters in this study included were presence or absence of punctum, relation of the mass to the overlying skin,
consistency, characteristics of borders, history of inflammation presence or
absence of discharge.
In conclusion, the
probability that the superficial tissue mass is an epidermal inclusion cyst
based on physical findings would include in descending order: punctum, consistency and delineable border. Presence of history of infection and presence
of discharge is not a reliable criterion to diagnose such disease. Moreover, the probability of diagnosing lipoma based on physical findings would be low using
parameters such as tethered to skin and presence of punctum
and a higher probability in diagnosing lipoma in
tumors presenting with soft, barely delineable borders.
REFERENCES
Brown EJ,
Brown AP, Fogarty B,
Brennen MD: A dermoid cyst
presenting as an epidermoid cyst in the malar region. Br J Plast Surg 2001 Mar; 54(2): 180
Domonkos, et al., Andrews’ Diseases of the Skin Clinical Dermatology 7th
Edition. W.B. Saunders Company. 1982
Moore C, Greer DM Jr: Sebaceous cyst extraction through mini-incisions. Br J Plast Surg 1975 Oct; 28(4): 307-9
Cribb GL, Cool WP, Ford DJ,
Harrison's
Principles of Internal Medicine 16th Edition
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