Abstract
Background:
Some alopecic diseases can be diagnosed by detailed history taking and physical examination, but in many cases, biopsy must be performed to make a definite diagnosis.
Aims and Objectives:
This study aimed to evaluate the clinico-pathological concordance of scalp lesions showing alopecia.
Materials and Methods:
We retrospectively reviewed the electronic medical records and biopsy slides of patients who underwent biopsy for evaluating scalp lesions showing alopecia. Based on the definitions of clinico-pathological concordances, scalp alopecic disease was evaluated.
Results:
A total of 121 patients were enrolled in the study. A total of 203 clinical differential diagnoses were made before performing a biopsy. Thirty-one patients showed full concordance, and 58 patients showed partial concordance; thus overall concordance was shown in 89 patients (73.55%). Folliculitis decalvans and alopecia areata showed a higher full concordance rate than average (P < 0.05), whereas dissecting folliculitis showed a lower overall concordance rate than average, and folliculitis decalvans showed a higher overall concordance rate than average (P < 0.05). The overall concordance rate of alopecia areata was 100% (P = 0.061).
Conclusion:
In diagnosing folliculitis decalvans and alopecia areata, which showed high full and overall concordance, performing a biopsy to make a definite diagnosis is not always necessary, especially when patients show typical clinical features. Dissecting folliculitis, which showed low overall concordance, was less likely to be suspected as a clinical differential diagnosis, making it difficult to distinguish based on clinical findings alone. Therefore, when it is suspected, a detailed evaluation including a biopsy is recommended.
KEY WORDS: Alopecia, biopsy, concordance, scalp
Introduction
Many patients visit the dermatologic clinic with the chief complaint of scalp alopecia, and it is a very important task for dermatologists to provide appropriate treatment through accurate diagnosis. In most cases, an alopecic disease diagnosis can be made through detailed patient history and physical examination. Many patients show typical patterns; however, some are difficult to diagnose solely based on clinical features. In particular, various alopecic diseases show the form of scarring alopecia in which follicular ostia are blocked and hair follicles are replaced by fibrosis. In these cases, pathological information must be obtained through a biopsy to make an accurate diagnosis.[1]
The concordance rate between clinical and pathological diagnosis of skin diseases is reportedly between 67% and 87%.[2,3,4,5,6] However, there have been no reports on scalp alopecic diseases. Therefore, this study compared and analyzed concordance rates between clinical and pathological diagnoses of scalp alopecic diseases.
Materials and Methods
This study included patients who visited the dermatology outpatient department of a single tertiary medical centre in South Korea from January 2010 to June 2021 and underwent a biopsy to evaluate scalp lesions showing alopecia. Among them, patients who showed hair loss due to the presence of a mass and patients who had insignificant biopsy results were excluded. All tissues were sampled using punch biopsy and stained with hematoxylin and eosin. The clinical diagnosis of this study was the initial impression made by the dermatologist who first treated the patient at the time of performing biopsy. It was not determined by several dermatologists, but was solely determined by the initial dermatologist. Regarding the pathological diagnosis, the corresponding author and the first author determined the most appropriate histological diagnosis together after careful reviews of the slides. After setting the clinical diagnosis and histological diagnosis for each slide in this way, the concordance tendency of these clinical diagnoses and pathological diagnoses in each disease was analyzed.
To define the clinico-pathological concordance of scalp alopecic diseases, we used the three definitions proposed by Al-Saif et al.[7] Full concordance was defined as an identical clinical and pathological diagnosis. Partial concordance was defined as the pathological diagnosis being among one of the clinical differential diagnoses recorded by the dermatologist. The overall concordance was defined as both full and partial concordance combined. Comparisons between concordance rates were made using the Chi-square test or Fisher's exact test. We used SPSS software version 26.0 for analysis, and a P value <0.05 was considered significant. This study was reviewed and approved by the Institutional Review Board (IRB) of Hallym University Sacred Heart Hospital (IRB number 2021-07-017-001). The date of approval is 2021-08-31.
Results
[Table 1] summarises the basic characteristics of the 121 patients who participated in this study. A total of 203 differential diagnoses were made for the 121 patients clinically, with an average of 1.68 differential diagnoses per patient [Table 2]. The most frequently suspected disease for differential diagnosis was seborrheic dermatitis (n = 23, 11.33%), followed by alopecia areata (18, 8.87%) and psoriasis (17, 8.37%). The included patients had a specific pathological diagnosis, resulting in a total of 121 pathological diagnoses [Table 3]. The most common pathological diagnosis was dissecting folliculitis (28, 23.14%), followed by folliculitis decalvans (17, 14.05%), psoriasis, seborrheic dermatitis, and discoid lupus erythematosus (13, 10.74%).
Table 1.
Characteristics of patients showing scalp alopecia
| Scalp alopecia | |
|---|---|
| Sex | |
| Male | 74 (61.16%) |
| Female | 47 (38.84%) |
| Age | 43.36±21.88 |
| Duration | |
| <6 months | 52 (42.97%) |
| ≥6 months | 43 (35.54%) |
| UK | 26 (21.49%) |
| Location | |
| Frontal | 9 (7.44%) |
| Parietal | 13 (10.74%) |
| Vertex | 78 (64.46%) |
| Occipital | 18 (14.88%) |
| UK | 3 (2.48%) |
| Biopsy method | |
| Punch biopsy | 121 (100%) |
Values are presented as number (%) or mean±standard deviation. UK=Unknown
Table 2.
Clinical differential diagnosis of scalp lesions showing alopecia
| Clinical differential diagnosis | Number |
|---|---|
| Seborrheic dermatitis | 23 (11.33%) |
| Alopecia areata | 18 (8.87%) |
| Psoriasis | 17 (8.37%) |
| Folliculitis decalvans | 16 (7.88%) |
| Dissecting folliculitis | 16 (7.88%) |
| Discoid lupus erythematosus | 14 (6.90%) |
| Cicatricial alopecia NOS | 12 (5.91%) |
| Lichen pilanopilaris | 10 (4.93%) |
| Tinea capitis | 8 (3.94%) |
| Folliculitis NOS | 7 (3.45%) |
| Acne keloidalis | 6 (2.96%) |
| Others | 56 (27.59%) |
| Total | 203 |
Values are presented as number (%)
Table 3.
Pathological diagnosis of scalp lesions showing alopecia
| Pathologic diagnosis | Number |
|---|---|
| Dissecting folliculitis | 28 (23.14%) |
| Folliculitis decalvans | 17 (14.05%) |
| Psoriasis | 13 (10.74%) |
| Seborrheic dermatitis | 13 (10.74%) |
| Discoid lupus erythematosus | 13 (10.74%) |
| Alopecia areata | 10 (8.27%) |
| Tinea capitis | 5 (4.14%) |
| Acne keloidalis | 4 (3.31%) |
| Frontal fibrosing alopecia | 2 (1.65%) |
| Lichen simplex chronicus | 2 (1.65%) |
| Trichotillomania | 2 (1.65%) |
| Others | 12 (9.92%) |
| Total | 121 |
Values are presented as number (%)
Among the 121 patients, 31 patients (25.62%) showed full concordance and 58 patients (47.93%) showed partial concordance; therefore, 89 patients (73.5%) showed overall concordance. We obtained the concordance rate for each disease and conducted statistical analysis. Significant results were shown for dissecting folliculitis, folliculitis decalvans, and alopecia areata [Table 4]. The full concordance rate was 47.06% for folliculitis decalvans (P = 0.038) and 80% for alopecia areata (P < 0.001). The overall concordance rate was 57.14% for dissecting folliculitis (P = 0.025) and 94.12% for folliculitis decalvans (P = 0.040). Although not significant, alopecia areata showed 100% overall concordance (P = 0.061).
Table 4.
Clinico-pathological concordance rates of alopecic diseases
| Alopecic disease | Full concordance | Partial concordance | Overall concordance | P value FC | P value OC |
|---|---|---|---|---|---|
| Dissecting folliculitis | 4/28 (14.28%) | 12/28 (42.86%) | 16/28 (57.14%) | 0.117 | 0.025* |
| Folliculitis decalvans | 8/17 (47.06%) | 8/17 (47.06%) | 16/17 (94.12%) | 0.038* | 0.040* |
| Psoriasis | 3/13 (23.08%) | 8/13 (61.54%) | 11/13 (84.62%) | 1 | 0.510 |
| Seborrheic dermatitis | 1/13 (7.69%) | 6/13 (46.15%) | 7/13 (53.84%) | 0.180 | 0.103 |
| Discoid lupus erythematosus | 2/13 (15.38%) | 10/13 (76.92%) | 12/13 (92.30%) | 0.511 | 0.181 |
| Alopecia areata | 8/10 (80%) | 2/10 (20%) | 10/10 (100%) | <0.001 | 0.061 |
| Tinea capitis | 1/5 (20%) | 3/5 (60%) | 4/5 (80%) | 1 | 1 |
| Acne keloidalis | 2/4 (50%) | 2/4 (50%) | 4/4 (100%) | 0.271 | 0.572 |
| Frontal fibrosing alopecia | 1/2 (50%) | 1/2 (50%) | 2/2 (100%) | 0.448 | 1 |
| Lichen simplex chronicus | 1/2 (50%) | 0/2 (0%) | 1/2 (50%) | 0.448 | 0.461 |
| Trichotillomania | 0/2 (0%) | 2/2 (100%) | 2/2 (100%) | 1 | 1 |
| Others | 0/12 (0%) | 4/12 (33.33%) | 4/12 (33.33%) | ||
| Total | 31/121 (25.62%) | 58/121 (47.93%) | 89/121 (73.55%) | □ | □ |
*: P value<0.05
Discussion
The concordance rate between clinical and pathological diagnosis of scalp lesions showing alopecia was 73.55%, a level corresponding to the concordance rate of skin diseases in general. In the existing literature, there was no study that separately presented the clinico-pathological concordance rate of the scalp, but one study showed a concordance rate of 77.1% when head/neck/scalp/hair was grouped together.[7]
Concerning full concordance, when a specific disease was diagnosed pathologically, it was clinically suspected without a differential diagnosis in only 25.62% of the patients. If only one differential diagnosis is considered, then the disease is strongly suspected. Folliculitis decalvans and alopecia areata, which showed high full concordance rates, were more solely clinically suspected due to their characteristic clinical features. Folliculitis decalvans is a representative disease of tufted hair. Therefore, if tufted hair presents with a pattern of cicatricial alopecia, it can be suspected as folliculitis decalvans.[8] In seven of the eight patients with folliculitis decalvans (87.5%) who showed full concordance, typical tufted hair was observed [Figure 1]; therefore, this finding may have influenced the clinical diagnosis. Similarly, alopecia areata showed high full concordance due to clinical findings such as characteristic exclamation point hairs, broken hairs, and black dots [Figure 2]. However, alopecia areata was suspected in 18 patients as a clinical differential diagnosis, but only 10 of them were pathologically diagnosed with this condition, and the other eight patients were diagnosed with other diseases through biopsy. Typical exclamation point hairs and broken hairs were observed in all eight patients with full concordance [Figure 2], but these characteristic clinical features were not clearly observed in the rest of the patients.
Figure 1.
Typical tufted hair in folliculitis decalvans (a), (b) Typical tufted hair is noted in patients diagnosed with folliculitis decalvans. Both patients showed full concordance between clinical and histopathological diagnoses
Figure 2.
Typical clinical manifestation of alopecia areata (a) Typical black dots and broken hair are noted in patients diagnosed with alopecia areata. This patient showed full concordance between clinical and histopathological diagnoses (b) Typical black dots, broken hair, and exclamation point hair are observed in dermoscopy
Folliculitis decalvans showed 94.12% (P = 0.040) overall concordance, which was the highest among the significant results; therefore, it was the alopecic disease with the highest clinico-pathological concordance. Alopecia areata showed 100% overall concordance (P = 0.061), which was almost significant. Hence, regarding the diagnosis of folliculitis decalvans and alopecia areata, because they show high clinico-pathological concordance rates, performing a biopsy to make a definite diagnosis is not always necessary especially when patients show very typical clinical features. However, in patients with ambiguous clinical features, biopsy should be performed to make a clear diagnosis.
In contrast, dissecting folliculitis showed a low overall concordance (57.14%, P = 0.025). This means that when dissecting folliculitis was diagnosed pathologically, it was also clinically suspected as dissecting folliculitis less often than average. Several cases were suspected to be different diseases clinically; therefore, dissecting folliculitis is difficult to distinguish based on clinical findings. Most clinically misdiagnosed patients were suspected to have an inflamed epidermal cyst or alopecic and aseptic nodules of the scalp. Inflamed epidermal cysts can show fluctuating nodules similar to dissecting folliculitis,[9] and alopecic and aseptic nodules of the scalp also need to be differentiated from dissecting folliculitis because they show clinically similar patterns.[10] As such, dissecting folliculitis can be misdiagnosed; therefore, when we see patients with similar clinical features, detailed evaluation, including biopsy, is required.
A limitation of this study is that it was a retrospective study. Second, although this research was conducted at a single tertiary medical center, there may be differences in making differential diagnoses between dermatologists. The authors believe that further prospective research that complements these limitations must be conducted.
In summary, the clinico-pathological concordance rate in scalp lesions showing alopecia was 73.55% in this study. Folliculitis decalvans and alopecia areata, which showed high full concordance, are more likely to be clinically suspected as the sole diagnosis due to their characteristic clinical features. They also showed high overall concordance, so performing a biopsy to make a definite diagnosis is not always necessary, especially when patients show typical clinical features. Dissecting folliculitis, which showed low overall concordance, was less likely to be suspected as a clinical differential diagnosis, making it difficult to distinguish by clinical findings alone. Therefore, when dissecting folliculitis is suspected, or patients show similar clinical features, a detailed evaluation including a biopsy is recommended. This study is meaningful in that it is the first to report the clinico-pathological concordance rate of scalp alopecic disease and may be helpful in alopecia diagnosis and treatment.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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