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A 45-year-old woman brings her daughter for evaluation of the daughter’s acne. However, during the appointment, an odd lesion is noted on the mother’s shoulder.
Once the daughter’s evaluation is completed, attention turns to the mother’s lesion, which she reports “has been there for years.” Until last year, it hadn’t changed—but since then, it has grown considerably and also darkened.
The patient has an extensive history of poorly tolerated sun exposure in her childhood and young adulthood. She says she is able to tan but “it only holds for a short time.”
EXAMINATION
The lesion, a 2.8-cm black plaque with irregular margins, is located on the crown of the right shoulder. The patient has somewhat sun-damaged, freckled type II skin.
Dermatoscopic examination reveals regularly spaced white pinpoint areas scattered over the lesion’s surface. Focally, there is definite black streaking and pigment clumping on the borders of the lesion.
The white spots are consistent with pseudocysts seen in seborrheic keratosis. But the clumping and streaming of pigment are features we might expect to see with melanoma.
What is the diagnosis?
DISCUSSION
This case illustrates at least two useful principles:
1. The “patient” is not always the one listed on the charge sheet. I’ve found at least four melanomas and innumerable basal cell carcinomas on friends and relations who happen to be in the room with “the patient.” I can’t pretend I didn’t see the lesion, whoever it’s on. Of course, we must prioritize the patient of record—but then turn our attention to the “new” lesion/patient.
2. There is no law that says a seborrheic keratosis (SK) cannot occur in the same location as a melanoma. It may be rare, but it’s not unheard of. In this case, there were signs of both; the only way to sort it out, safely, was to excise the entire lesion and submit it to pathology. This provides the pathologist with adequate tissue to judge the whole lesion.
As it happens, this case entailed both diagnoses: the SK on the surface and a melanoma in situ on the underside. The latter was confined to the upper epidermis (ie, did not penetrate into the dermis). Re-excision with 5-mm margins was done, just to be on the safe side. Had the melanoma been left in place, it could have become invasive with time (though it might have taken years).
SKs are the most common benign lesions seen in dermatology practices—this patient had several others on her trunk—but can coincide with other lesions/diagnoses (eg, cancer). The oddity of the shoulder lesion’s appearance (a shape known as the black sheep sign), along with the patient’s fair, sun-damaged skin, prompted dermatoscopic examination.
With the power to visualize lesions under polarized light at 10x magnification, we have developed an entire body of knowledge about the features of benign vs malignant lesions—making the dermatoscope a common and valuable tool in dermatology practices across the world.
TAKE-HOME LEARNING POINTS
• Although a rare occurrence, seborrheic keratosis and melanoma (or another lesion) can co-exist in the same location.
• The odd appearance of the lesion, combined with the patient’s fair, sun-damaged skin, was enough to trigger a closer look.
• Dermatoscopic examination (10x magnification with polarized light) can identify features of benign and malignant lesions. In this case, both were found.
• Complete excision is the gold standard for biopsy of lesions suspicious for melanoma.
A 45-year-old woman brings her daughter for evaluation of the daughter’s acne. However, during the appointment, an odd lesion is noted on the mother’s shoulder.
Once the daughter’s evaluation is completed, attention turns to the mother’s lesion, which she reports “has been there for years.” Until last year, it hadn’t changed—but since then, it has grown considerably and also darkened.
The patient has an extensive history of poorly tolerated sun exposure in her childhood and young adulthood. She says she is able to tan but “it only holds for a short time.”
EXAMINATION
The lesion, a 2.8-cm black plaque with irregular margins, is located on the crown of the right shoulder. The patient has somewhat sun-damaged, freckled type II skin.
Dermatoscopic examination reveals regularly spaced white pinpoint areas scattered over the lesion’s surface. Focally, there is definite black streaking and pigment clumping on the borders of the lesion.
The white spots are consistent with pseudocysts seen in seborrheic keratosis. But the clumping and streaming of pigment are features we might expect to see with melanoma.
What is the diagnosis?
DISCUSSION
This case illustrates at least two useful principles:
1. The “patient” is not always the one listed on the charge sheet. I’ve found at least four melanomas and innumerable basal cell carcinomas on friends and relations who happen to be in the room with “the patient.” I can’t pretend I didn’t see the lesion, whoever it’s on. Of course, we must prioritize the patient of record—but then turn our attention to the “new” lesion/patient.
2. There is no law that says a seborrheic keratosis (SK) cannot occur in the same location as a melanoma. It may be rare, but it’s not unheard of. In this case, there were signs of both; the only way to sort it out, safely, was to excise the entire lesion and submit it to pathology. This provides the pathologist with adequate tissue to judge the whole lesion.
As it happens, this case entailed both diagnoses: the SK on the surface and a melanoma in situ on the underside. The latter was confined to the upper epidermis (ie, did not penetrate into the dermis). Re-excision with 5-mm margins was done, just to be on the safe side. Had the melanoma been left in place, it could have become invasive with time (though it might have taken years).
SKs are the most common benign lesions seen in dermatology practices—this patient had several others on her trunk—but can coincide with other lesions/diagnoses (eg, cancer). The oddity of the shoulder lesion’s appearance (a shape known as the black sheep sign), along with the patient’s fair, sun-damaged skin, prompted dermatoscopic examination.
With the power to visualize lesions under polarized light at 10x magnification, we have developed an entire body of knowledge about the features of benign vs malignant lesions—making the dermatoscope a common and valuable tool in dermatology practices across the world.
TAKE-HOME LEARNING POINTS
• Although a rare occurrence, seborrheic keratosis and melanoma (or another lesion) can co-exist in the same location.
• The odd appearance of the lesion, combined with the patient’s fair, sun-damaged skin, was enough to trigger a closer look.
• Dermatoscopic examination (10x magnification with polarized light) can identify features of benign and malignant lesions. In this case, both were found.
• Complete excision is the gold standard for biopsy of lesions suspicious for melanoma.
A 45-year-old woman brings her daughter for evaluation of the daughter’s acne. However, during the appointment, an odd lesion is noted on the mother’s shoulder.
Once the daughter’s evaluation is completed, attention turns to the mother’s lesion, which she reports “has been there for years.” Until last year, it hadn’t changed—but since then, it has grown considerably and also darkened.
The patient has an extensive history of poorly tolerated sun exposure in her childhood and young adulthood. She says she is able to tan but “it only holds for a short time.”
EXAMINATION
The lesion, a 2.8-cm black plaque with irregular margins, is located on the crown of the right shoulder. The patient has somewhat sun-damaged, freckled type II skin.
Dermatoscopic examination reveals regularly spaced white pinpoint areas scattered over the lesion’s surface. Focally, there is definite black streaking and pigment clumping on the borders of the lesion.
The white spots are consistent with pseudocysts seen in seborrheic keratosis. But the clumping and streaming of pigment are features we might expect to see with melanoma.
What is the diagnosis?
DISCUSSION
This case illustrates at least two useful principles:
1. The “patient” is not always the one listed on the charge sheet. I’ve found at least four melanomas and innumerable basal cell carcinomas on friends and relations who happen to be in the room with “the patient.” I can’t pretend I didn’t see the lesion, whoever it’s on. Of course, we must prioritize the patient of record—but then turn our attention to the “new” lesion/patient.
2. There is no law that says a seborrheic keratosis (SK) cannot occur in the same location as a melanoma. It may be rare, but it’s not unheard of. In this case, there were signs of both; the only way to sort it out, safely, was to excise the entire lesion and submit it to pathology. This provides the pathologist with adequate tissue to judge the whole lesion.
As it happens, this case entailed both diagnoses: the SK on the surface and a melanoma in situ on the underside. The latter was confined to the upper epidermis (ie, did not penetrate into the dermis). Re-excision with 5-mm margins was done, just to be on the safe side. Had the melanoma been left in place, it could have become invasive with time (though it might have taken years).
SKs are the most common benign lesions seen in dermatology practices—this patient had several others on her trunk—but can coincide with other lesions/diagnoses (eg, cancer). The oddity of the shoulder lesion’s appearance (a shape known as the black sheep sign), along with the patient’s fair, sun-damaged skin, prompted dermatoscopic examination.
With the power to visualize lesions under polarized light at 10x magnification, we have developed an entire body of knowledge about the features of benign vs malignant lesions—making the dermatoscope a common and valuable tool in dermatology practices across the world.
TAKE-HOME LEARNING POINTS
• Although a rare occurrence, seborrheic keratosis and melanoma (or another lesion) can co-exist in the same location.
• The odd appearance of the lesion, combined with the patient’s fair, sun-damaged skin, was enough to trigger a closer look.
• Dermatoscopic examination (10x magnification with polarized light) can identify features of benign and malignant lesions. In this case, both were found.
• Complete excision is the gold standard for biopsy of lesions suspicious for melanoma.
