When in doubt look up to the skies A skywatchers perspective in dermatology

Abstract

A aerial and Celestial based eponymous review in dermatology

Full text

1© 2022 Indian Journal of Dermatology, Venereology and Leprology - Published by Scientic Scholar
Introducon
Dermatologists in the past have been on the lookout for
visual cues and similarities for the nomenclature of clinical
conditions and signs and have been comparing them to
various foods, animals, birds, and objects that have a common
occurrence in everyday life. This has led to the easier memory
and retention of complex dermatological nosology that would
have been long forgotten otherwise. This article highlights
the aerial perspective on such terminology.
1. Asteroid bodies: These are stellate acidophilic
inclusion bodies with 20–30 radial projections seen
in the cytoplasm and staining positively with PTAH,
aldehyde fuchsin, and Masson trichrome stain.
They are composed of microlaments made up of
tyrosine-containing protein. These are not specic for
any condition and can be seen in any granulomatous
reaction pattern, being most commonly observed
in sarcoidosis and sporotrichosis. Other rare
conditions with asteroid bodies include mycobacterial
infections, other deep fungal infections, foreign body
granulomas, necrobiotic xanthogranuloma, annular
elastolytic granuloma, schistosomiasis and soft tissue
tumours like broxanthosarcoma.1
2. Aurora borealis: It is a distinctive pattern seen in
distal subungual onychomycosis due to the irregular
matte pigmentation of different colours in parallel
patterns thus giving similarity to the northern lights.
It arises due to the presence of underlying fungal
colonies and accumulated scales and subungual debris
beneath the onycholytic nail plate.2
3. Chicago sky blue stain: Named due to its bright blue
colour that it imparts, it is a fungal stain mainly
used as an adjunct to potassium hydroxide mount
mainly for diagnosing dermatophyte infections and
pityriasis versicolor. It increases the colour contrast
and eases identication of varied fungal morphology
by imparting a bluish colour. It can be used with a
light microscope unlike calcouor white stain and
also is better than Parker blue ink in the identication
of dermatophytes, hence serves as a useful alternative
for Swartz Lamkins stain for dermatophyte.3,4
4. Cloudy sky pattern: Described as a dermoscopic pattern
in idiopathic guttate hypomelanosis characterized
by ill-dened whitish homogeneous round macules
coalescing to form irregular, polycyclic macules
with surrounding hyperpigmentation [Figure 1].
It has also been described as a clue for the diagnosis
of periorbital syringomas.5,6
When in doubt look up to the skies: A skywatchers
perspective in dermatology
Aravind Sivakumar, Rashmi Kumari
Department of Dermatology and STD, Jawaharlal Institute of Postgraduate Medical Education & Research, Puducherry, India.
How to cite this article: Sivakumar A, Kumari R. When in doubt look up to the skies: A skywatchers perspective in dermatology. Indian J Dermatol Venereol
Leprol doi: 10.25259/IJDVL_824_2021
Corresponding author: Dr. Aravind Sivakumar, Department of Dermatology and STD, Jawaharlal Institute of Postgraduate Medical Education &
Research, Puducherry, India. aravinddermat@gmail.com
Received: August, 2021 Accepted: February, 2022 EPub Ahead of Print: July, 2022 Published: ***
DOI: 10.25259/IJDVL_824_2021 PMID: ***
Figure 1: Cloudy skin pattern observed on dermoscopy
in idiopathic guttate hypomelanosis
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Indian Journal of Dermatology, Venereology and Leprology | Volume xx | Issue xx | Month 2022
2
Sivakumar, et al. Aerial appearances in dermatology
5. Comet tail sign: This nds its place in more than
one context in dermatology. Firstly in vitiligo where
comet tail pattern observed dermoscopically can be
an indicator of disease activity.7 Comet sign has also
been described in infestation with the mite Pyemotes
ventricosus which presents as erythematous macules
tapering distally with a linear tract resembling a comet,
which might herald the onset of lymphangitis.8 Comet
tail lesions are also seen in the fundus of patients with
pseudoxanthoma elasticum and are pathognomonic for
this condition. These arise earlier than angioid streaks
and peau d’ orange appearance which are nonspecic.9
6. Craters of the moon: It refers to the specic
trichoscopic pattern seen in alopecia areata
characterized by extensive depressed yellow dots and
signies poor prognosis. It also helps to differentiate
from the yellow dots of the DLE which lack these
depressions on trichoscopy.10
7. Delta wing sign: Refers to the dark triangular
V-shaped proximal portion of the scabies mite when
examined dermoscopically while the rest of the body
appears translucent resembling a delta wing jet. Also
referred to as the triangle sign /hang glider sign or
spermatozoid appearance.11
8. Eclipse nevus: This is a particular type of scalp nevus
most seen in children. Characterized by the presence
of tan centre which may be elevated surrounded by
an irregular brownish rim with a stellate appearance
resembling a solar eclipse. It may bear resemblance
to a cockade nevus which has the reverse of this
pigment pattern. Clinically it is a benign lesion that
shouldn’t raise any alarming signs.12
9. Galaxy sign: Although not a cutaneous sign it is
seen in sarcoidosis. It might be an important imaging
clue for diagnosis, where there is a single pulmonary
nodule with surrounding smaller nodules in high
resolution computed tomography (HRCT) of the chest
which is due to the less dense arrangement of smaller
satellite nodules around the main nodule hence
resembling a galaxy.13
10. Haloes: Halo nevus or Sutton’s nevus refers to the
appearance of rim of depigmentation surrounding
benign melanocytic nevi. Seen most commonly
in children, multiple halo nevi may be associated
with atopic dermatitis or autoimmune disorders like
vitiligo or Hashimoto thyroiditis.14 Halo phenomenon
or Meyerson phenomenon refers to the symmetrical
area of erythema and scaling surrounding a lesion
such as melanocytic nevus due to eczematisation.
This can also be observed in molluscum contagiosum,
seborrheic keratosis and capillary malformation.15
11. Jet with contrail appearance: Seen in scabies
dermoscopy where the burrow with the mite at its end
resembles the trail of a jet plane.16
12. Lichtenberg gures: Also referred to as arborescent
burns or ligree burns, these are skin manifestations
which are pathognomonic of lightning injury either
directly or as a side ash from surrounding objects
like trees causing a supercial burn in a fern or
feather-like pattern. It is a transient phenomenon
lasting from 30 minutes up to 2 days and disappears
without pigmentation.17 Sometimes similar appearance
can be observed in pressure-induced vasodilatation
causing arborescent appearance which can be
differentiated with diascopy.18
13. Lone star ticks: Refers to Ambylomma americanum
due to the prominent white dot on the back of
the adult female. It serves as a vector for various
rickettsial diseases such as Rocky Mountain spotted
fever, Q fever, tularaemia, ehrlichiosis, and southern
tick-associated rash illness (STARI).19
14. Moon facies: Coined by Harvey Cushing, an
American neurosurgeon who rst described it in
people with Cushing’s syndrome who had round
faces. It occurs due to the excessive fat deposition
on the face that accompanies primary or exogenous
Cushing’s syndrome [Figure 2].20
15. Half-moon appearance of lunula: Lunula is the visible
portion of the distal nail matrix that appears whitish
with distal convex and proximal straight borders
[Figure 3]. It is most prominent on the thumb, index
nger, and great toe and guides the shape of the nail
plate distally. Abnormalities of the lunula i.e., micro
lunula, macrolunula, erythema, lunular dyschromia all
point to underlying systemic disorders.21
16. Nebuloid appearance: Seen in the dermoscopy of
idiopathic guttate hypomelanosis where there are
whitish homogeneous areas with indistinct borders.
Figure 2: Moon facies seen in exogenous Cushing syndrome due to
steroid intake

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Sivakumar, et al. Aerial appearances in dermatology
Nebula refers to clouds of celestial dust and gases
usually describing distant galaxies which are indistinct.6
17. Papular epidermal nevus with ‘skyline’ basal layer
(PENS): Presents as single or multiple skin-coloured
keratotic skin lesions that do not follow the lines of
Blaschko, usually present since birth. Histologically
it has columnar cells with uniform small nuclei in a
palisaded pattern in the basal layer like a ‘skyline’ or
‘eyeliner’ appearance.22
18. Pink rim sign: In the dermoscopy of melanoma
there are varied shades of pink and the location in
the periphery suggests the presence of underlying
invasive melanoma. This resembles the pink rim of
the sun at sunset or the lunar eclipse.23
19. Raindrops: Raindrops are described in a myriad of
conditions, most seen in miliaria crystallina [Figure 4]
where the accid vesicles are seen on a non-
erythematous base. Raindrop pigmentation has been
described in arsenic toxicity which is characterized by
truncal hyperpigmentation with scattered depigmented
macules present over it. Sometimes the distribution of
seborrheic keratosis over the back resembles that of
raindrops and stream appearance.24
20. Rainbow appearance: It is a specic appearance
seen in the polarized dermoscopy where there is
the presence of bluish-red discolouration along
with varied colours of the rainbow. It occurs due
to diffraction of the incident light over the skin due
to the difference in refractive indices of the layers
of skin termed optical dichroism. Classically seen
in Kaposi sarcoma it can also be seen in atypical
broxanthoma, basal cell carcinoma, aneurysmal
dermatobroma, Merkel cell carcinoma, and acral
pseudolymphomatous angiokeratoma.25
21. Red half-moon nail sign: Seen particularly in
COVID-19 infection where there are reddish half-
moon-shaped convex bands over the margin of the
lunula due to the localized microvascular injury to the
distal subungual arterial arcade.26
22. Subungual red comets: This is a specic nail nding
seen on dermoscopy in tuberous sclerosis complex.
Characterized by the presence of tortuous capillaries
with surrounding whitish halo and can be associated
with periungual or subungual bromas. It can be
differentiated from splinter haemorrhage by the
absence of whitish halo, shorter length, and straight
linear appearance reaching the distal free end of the
nail plate.27
23. Satellite lesions: This is common terminology for
the arrangement of multiple smaller lesions around
larger skin lesions situated nearby. It is usually
seen in conditions such as borderline tuberculoid
Hansen’s, congenital melanocytic nevus [Figure 5],
and exural candidiasis.28
24. Setting sun sign: Describes the dermoscopic
picture characterized by yellow-orange background
Figure 3: Half-moon appearance of lunula
Figure 4: Raindrop-like appearance in miliaria crystallina
Figure 5: Multiple satellite lesions seen in congenital melanocytic nevus

Indian Journal of Dermatology, Venereology and Leprology | Volume xx | Issue xx | Month 2022
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Sivakumar, et al. Aerial appearances in dermatology
on the skin resembling frosting that occurs during
the time of the year when it snows from the skies.
It occurs due to the crystallization of urea and other
nitrogenous waste products onto the surface of the
skin also referred to as ‘uridrosis’ or ‘urinous sweat’.40
32. Weather-beaten appearance: Resembles skin that
is damaged due to chronic sun damage during
the summer season, clinically presents as shallow
puckered linear or elliptical scars accompanied by
waxy thickening and sclerodermoid changes. It is
described classically in children with erythropoietic
protoporphyria and lipoid proteinosis.41
Declaration of patient consent
Informed consent for publication of images has been taken
from the patients by the authors.
Financial support and sponsorship
Nil.
Conicts of interest
There are no conicts of interest.
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29. Stars in heaven: Seen in cases of heavy metal
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of silver deposits seen around the eccrine glands and
dispersed in the dermis which in darkeld microscopy
appears as brilliantly refractile white particles against
a black background.38
30. Stellate appearance: Stellate pseudoscars are whitish
irregular or star-shaped pseudoscars mostly seen in
elderly individuals over the photo exposed sites, but
can also arise due to topical steroid abuse.39
31. Uremic frost: It is a sign of severe azotaemia seen
in patients with end-stage renal disease characterized
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